I downloaded their items DB (which they publish) and created a program that downloaded prices from eve-central and figured out the best tech 2 things to build based on predictions of how well the item would be selling in a week and what skills my builder had or could get in that time.
Took me a month or two. Once it was finished I only spent about 2 weeks actually building stuff. The UI is so terrible and to make a decent profit with the fairly low level character you had to set off jobs in the morning too. That was the beginning of the end for me coupled with my then alliance going under (roadkill).
Good programming practice though.
Crikey, just checked, was almost 4 years ago. I re-subbed again for a month after the monocle fiasco, hadn't really changed much since then. They seem to be focusing on their new products.
I played the margins on nullsec loot (often melted and sold for pennies), shipping it off to Jita (using outsourced freighters) and selling for significantly more. Made twenty or thirty billion simply playing the margins between nullsec and highsec.
Another few billion were made by importing "compressed" minerals for all the capital ship producers.
Moonmining was a lot of fun because of the logistics involved. Ditto for the wormhole exploration.
At one point I wrote a bot that sat in Jita and basically daytraded, playing the spread between bid and ask. I lost interest in Eve around that time because of work and a social life, but it was a fun project to work on (lots of OCR involved).
All that said, I was small fish compared to others in my corp. One guy took an investment of 100bn from our corp and used that capital to finance an "Officer Loot Buyback" program. Basically, ratters were bringing in a lot of officer loot, but that stuff is really only worthwhile in Jita, and you had to babysit contract. Most players can't be bothered to sell it themselves...but they know it is worth good money.
This guy purchased the loot at a 10-60% discount simply because of convenience. Ratters were happy with getting some money, he shipped it off to the markets and made the difference.
He quit eventually, having repaid the entire 100bn investment and making several times that in profit. Pretty crazy (for an internet spaceship game)
Personally I'd tell anyone else to avoid it having been through it and come out the other side. It just doesn't give you much for the time spent. The ships look great, but don't expect either elite or tie fighter.
The pve is terrible, though diverting enough for the first month or two. Unless you really like collecting stuff and making a mega pimp mobile, it rapidly becomes extremely dull.
One of the addictive things about it is how 'risky' the pvp is as the ships you use are worth days in mind numbingly boring grinding. There is a heavy death penalty if you are using a 'good' ship and it's one of the only things that actually makes it fun, you do get an adrenaline rush from it. But the actual combat lasts 30 seconds-1 minute and it often will have taken you hours to find that one combat. Get caught by the wrong thing and you're guaranteed to die.
There are very few massive fleet battles. In fact more time is spent with FCs avoiding the enemy than actually fighting them and when you do get in a battle you die as soon as you're targeted as it's 100s of people shooting you in tandem. The weapons have far too long ranges so the most effective tactic is everyone shoots at the same target. Do not choose a name that starts with a-f, you will always be primaried.
Although there are more creative ways to make in game credits than grinding, you can even buy it (they have regulated RMT).
Be aware that they allow in game scamming and the game is pretty rough round the edges so it's very easy to fall for. Often you'd not think that's the way a mechanic is supposed to work.
Also there are generally 2 or 3 ships that are terribly overpowered at any one time in game. They usually take a year to fix them. If you plan going pvp it's worth finding out with the FOTM ships are from the beginning
As someone else says get a good corp quick. Reddit have their own one.
TLDR; If you want to get a taste of what it's like actually playing eve, open up a chat window with some friends and then 'spin' the ship in that web GL browser.
That's what you'll spend most of your time doing in eve online.