Lately I've been trying to figure the best way for me to make ISK. There are a lot of factors to take into consideration when trying to earn ISK the largest factor being "how much are you willing to risk". Other factors include but are not limited to; enjoyment, investment, time, and skill. Below are various ways that I've noticed or been part of so far. Once again to anyone reading my blogs please remember that I'm a noob and generally don't have a veterans point of view. Feedback is definitely welcome. Please feel free to tell me that I'm stupid and don't know what the hell I'm talking about.
Mining: Mining can be decent for earning ISK if you have the right skills. Mining in high sec is low risk but not entirely risk free. Right now I can fly a mining barge so in high sec I can pull in about 4-5 million ISK in one retriever over the course of about an hour. Not horrible, but definitely not going to retire on that. I know miners in my corp with much higher skills that can pull in about 40 million in an hour, in high sec. The only real risks in high sec are people either stealing your cans or suicide ganking you. Now, low sec mining and null sec mining can be much more profitable, but much more dangerous. I don't have the numbers regarding how much per hour you can make, but the ore found in low and null are drastically more valuable. the real problem with mining (in my opinion), is that it's painfully boring. It's not a bad gig if you own two characters and your alt can be mining while you're doing something else, just keep a wary eye on your miner and don't go afk you'll come back to you sitting in your pod either in space or back at a station.
Trade: I don't know a lot about trade, but I've heard it can be fairly lucrative IF you have the money to invest to get started. Trade will require that you have the ability to haul large quantities of items to really make it worth your while. Again the more risk you are willing to take the more you can make. Lots of low sec stations don't have a lot of goods for sale, so if you can find out what's commonly purchased in an area, and help stock up those stations you can definitely earn a lot of ISK. Unless you're flying a blockade runner, you'll be taking a lot of risk to transport goods into areas where you are a prime target to get popped.
Missions: Missions aren't a bad way to earn ISK and depending on your skills can be anywhere from low risk to high risk. On level 4 missions in high sec you can earn 10-100 million ISK per mission (including bounties, salvage, and mission rewards). You also earn LP (loyalty points) for the faction that you're running missions for which can then in turn be used to purchase faction goods, which can then be sold for tons of ISK. Now level 4 missions can be definitely challenging for the player fairly new to the game, so noobs (like myself) will typically fleet up with a few other noobs and take on the missions. This will make the missions easier to tank, however you are now splitting your loot with as many people that helped with the mission. They also have level 5 missions out in low sec (which I have not yet tried) that are more difficult, more risky, and much more profitable. Missions can definitely be a lot of fun, for a while, but they will eventually get boring.
Ratting: Ratting is the exercise of traveling to asteroid belts and anomalies and killing NPC pirates to earn the bounties and loot associated with them. First off, don't even bother with this exercise in high sec. High sec pirates are not worth taking the time to try and find and kill. Yeah, you can get lucky every now and then and find a decent bounty, but from what I've seen it's not worth your time. Low Sec and Null Sec is where ratting turns into a very profitable method of making ISK. Low sec and Null sec rats can also occasionally carry faction mods on them which can then be looted and sold for loads of ISK. Ratting in wormholes can be done as well, but wormhole rats don't have bounties on their heads. They do carry very nice loot sometimes so this can still be a very profitable way to earn ISK. There are loads of risks involved with ratting, depending where you are choosing to do it. In low sec you have to worry about pvp players jumping in and attacking you while you're in the middle of ratting. In null sec you have to worry about this as well, and lots of systems are "claimed" and people don't take very kindly to you earning ISK on their property. The same can be said for wormhole space, if the wormhole is occupied by a corporation you can definitely expect them to be hostile if they find you in their wormhole, killing their rats.
Faction Warfare: I dabbled with faction warfare for a few days and decided I wasn't really ready for it. I definitely saw tons of potential to make ISK, but you also have to be willing to lose a lot of ISK to earn it. Faction warfare in a nutshell is when you join one of the four races and decide that you want to help the militia forces go to war. Then you either help defend your space or go and attack another race's system and conquer it. There is a lot more to it than that, but overall you earn LP when you capture strongholds, and then if you earn enough LP you can turn it in for faction mods which can then be sold for lots of ISK. If you're dedicated to this you can most definitely earn yourself over a billion ISK a month, but the risk is high and at time can either be very exciting, or very very boring.
Scams: Do you have a high level of "moral flexibility"? Then scams may be for you. There are hundreds of scams out there ranging from "Hey give me money and I'll double it for you", to contracts to trick you, or huge corporation takeovers that can change the dynamics of Eve for everyone. I know I'm still new and still consider myself to possess decent morals in the game, but for some people they don't care at ALL about other people in the game and would pod their own mother for a few ISK. Personally I'm not a fan of scammers at all and I really find the people that spam the chat channel with stupid scams to be the most annoying of all. To me I put them at same level as telemarketers and used car salesmen. I just end up blocking them and wondering who would possibly be stupid enough for fall for their jokes, but people do, so people keep scamming.
Ninja Salvage: Ninja salvage is the act of stealing someone else's salvage (not the loot) that you had no part in creating. Using salvage drones or a salvager on a wreck does not give you a criminal tag allowing people to shoot you. If you take the loot inside the salvage then you get the suspect tag, but not for just salvaging the wreck. Personally I can't stand ninja salvagers. The ONLY time I think it's ok to "Ninja Salvage" is if you enter a room with wrecks and nobody is there running the missions (make sure they aren't just in the next room through the acceleration gate). Last week we had a ninja salvager come into our room with a Sarum Magnate and start salvaging while we were still running the mission. We had one of our mission runners suicide gank him for doing it. He was carrying a sisters of eve probe launcher, plus a few other cheap faction mods, and we ended up looting about 50-60 million in loot off of him. He was pissed and didn't understand why we would choose to be blown up and lose a ship just to protect our salvage. Well, the point was it was OUR salvage and he was stealing it. We didn't know his ship would drop that much loot, but also explained to him that if he's going to be stupid and steal other people's stuff that next time he probably shouldn't carry such expensive stuff on him. He had some nasty words to say and left the conversation.
Gate Camping: Ahh gate camping. If you have been playing Eve for longer than a week you probably already know what gate camping is. This is a risky way to make ISK (More risk for the less skills you possess), but can earn you quite a bit in ISK if you're good at it. Just remember there is always someone better than you, somewhere.
Manufacturing: Almost everything bought and sold in eve in manufactured by someone. Items don't get magically show up for sale at the station you go visit. Someone had to take the time to buy a blueprint, research it, obtain the materials to build it, manufacture it, and then put it up for sale. Every round of ammo you fire came from someone that built it. Ships, ammo, and common mods for your ships are very nice ways to make extra ISK. To be good at manufacturing you need to have the proper skills or you'll end up wasting more materials making the items and losing potential ISK. To make some serious ISK you can try and acquire some Tech 2 blueprints.Tech 2 blueprints are not easy to come by and not cheap when you do find them. If you can get your hands on a tech 2 blueprint that is for a commonly purchased item, and you have the skills to produce that item efficiently, you can make ridiculous amounts of ISK. The only real risk is losing money on the market, and nobody buying your stuff. If that happens, you just cancel the sell order, change the price, and maybe move locations.
Planetary Interaction: Planetary Interaction, or PI, is the method of placing command centers on planets, harvesting materials from that planet and you can either sell those materials or use them for manufacturing various items such as fuel for Player Owned Stations or POS'. We have a guy in our corp that makes an extra 100 million ISK a month doing PI. It doesn't take a large commitment from him in the ways of time, and is also very low risk. Although for some reason when I try it, 50% of the time when I launch my materials into space to get, the cargo container either doesn't show up or burns up and I lose all the materials. I've given up on it for now, but I'll probably start it back up again soon for a good supplemental income. Low Sec, Null Sec, and Wormhole Space planets have TONS of materials to be harvested. High sec isn't a very lucrative place to do PI, but you can earn a little more ISK if you're willing to do it.
Owning a corporation: CEO's and members on the board of directors for a corp also have the potential to make ISK. CEO's are able to set a tax rate on members of their corp, meaning that when members of the corp earn money on various transactions, the corporation takes a cut. For example, if you are a CEO and you have 10 members in your corp, and those 10 members collectively earn 200 million ISK in a month running mission, and you have a 10% tax rate, then you just made 20 million ISK. Now all this comes with a catch. Sure you just made 20 million ISK, but you are typically expected to provide some kind of services or use corporation money to do various things that help the corp. A lot of corporations have a ship replacement program that someone in the corp typically manufacturers one type of ship really well, like a destroyer or frigate. They may have hundreds of these ships sitting in the hanger just collecting dust and when members of their corp lose a ship, they can take one of these with no questions asked. The materials to build those ships may come out of the corporation wallet. If you own a POS you need to be able to put fuel in it, so you need to make sure you earn a few hundred million ISK in taxes to afford to buy your fuel, or have someone manufacture it. There are corporations out there with thousands of members each contributing to the corporation wallet, and there have been instances of hundreds of billions of ISK being in a wallet, and someone takes it all out, keeps it, and quits the corp. Only trusted people should have access to the corporation wallet, and you shouldn't trust anyone, so to be safe only you should have access unless you're willing to take the risk that someone can just walk away with your corporation funds.
These are only some of the common methods of earning ISK, and only ways that I in my very limited knowledge are able to speak about. There are other ways such as moon goo, incursions, and others that I have limited to no experience to be able to talk about. Some day I'll write another one of these once I realize that everything I just wrote here is probably wrong and out of date :)