Every new pilot must drive toward some way to earn ISK in New Eden. At first income is fairly slow and sometimes it is not obvious if you're doing it right. This is just a very high level list of the most common ways to make ISK for new pilots. More experienced pilots will have already discovered their 'best" ways. These are all ways to make ISK in Empire and near Low Sec. The rules for 0.0 are different.
The ways to make ISK boil down to these activities: Mining, PvE Missions, Exploration plundering, Wormhole plundering, Creative marketing, Buy it, and Piracy.
You probably know how this works. Chew on belt rocks and sell the Ore/Minerals. You want to plan for Mining Barges and high Refining skills. ISK potential is entirely reliant on your yield rate (the yield of your mining lasers/strip miners). Higher yields = more ISK regardless of what rock you are mining.
Missions are repetative, but steady. If mission running is really your goal, then drive toward the "better" PvE ships; the Drake, Raven, and Dominix. The Drake/Raven are Shield/Missile ships while the Dominix route is Armor/Drones. Plan accordingly. ISK generation between Mining and Missions is fairly even at high levels. Experience will allow you to hone in on the best ways to make ISK for each. Missions make ISK based on Rewards, Bounties, dropped Modules, and Salvage. You want to focus on increasing your rate of misison completion and pick an appropriate level of time spent on looting/salvage.
By using scan probe launchers and probes you can find hidden places in space. This income is wildly erratic where you make score nothing for a couple of days and then discover an item worth 10's of millions. You will need to focus on skills to enhance probing and ships with probe advantage (like covert ops). You may also end up needing PvE support to deal with NPC mobs in exploration sites. But finding the sites is longer part of the process. You can always ask for help to clear out/tank a site.
These "Unknown" Cosmic Signatures are found via Exploration above. But while Empire Exploration will always be pretty limited value, Wormhole pundering will have a much higher return. But you will need to have pretty good PvE skills to deal with the Sleeper rats found in WH's. Salvaging Sleeper wrecks get a different sub-set of salvage parts used in T3 construction. Melted Nanoribbons sell for 4-5 million ISK each. You can harvest these off "frigate" sized Sleepers allowing even modest skill pilots a way to make ISK. Wormholing is tricky and variable. You'll want to focus on battlecruiser sized ships like the Drake and Hurricane.
Using the markets takes a bit of a shrewd eye and an accountant's mind. But even a noob pilot can begin to make ISK by trading and transporting minerals. You will require some initial capital ISK to start. You may need a solid 500 million ISK to start (see below). The idea is classic "buy low and sell high." Target primary markets are Rens, Jita, Amarr, and Dodixie. Fat haulers and Freighters are helpful.
Buy Game Time Codes with your own cash and sell them on the forums or through PLEX in game. Each code can probably score between 600-800 million ISK. Great for those cash rich / time poor pilots.
Lie, cheat, murder, and steal. Gank ships in low sec... in particular hapless miners. Loot their strippers and sell them. Look for T1 haulers, cargo scan them, and gank the ones full of multi-million ISK BPO's, faction modules, or whole ships (like Hulks). Scan for private Courier Contracts that have low deposits, accept them and then break them... sell the contents for your own profit. Post stupid contracts "giving away" items that really require the victim to give you oodles of ISK. Post shuttles on the market for 8,000,000 ISK. Run bogus lotteries. Beg for ISK. Ninja salvage on other people's missions. Can flip. Etc. All you really have to do to be a pirate is know the game mechanics and exploit them.