One thing I have learnt in my three years is to have more than one income stream. ISK is the life blood of EVE and whilst it's nearly impossible to have no money, having very little limits what you can do.
This is one of the most wonderful things about EVE, there are multiple ways to generate ISK and you are never locked into one method, you are free to adapt and change how you do things.
So it pays (ha!) to have more than one income stream. Some of the most common ones are:
- Market Trading
- Industry / Manufacturing
- Mining (ore/ice and/or moon)
I'm sure there are variations I've missed but those are the eight main ones that come to mind and certainly everyone should have their ISK making spread across at least two of these.
When I started out in EVE it was mining that was my main income, this evolved into some manufacturing (which is logical) but I never was happy with what I was making. So I started doing Market Trading, this added a nice increase in ISK but it can be time consuming to manage hundreds of buy/sell orders and keep track of the market (there are tools available to help but again it's not something for a casual evening or two a week).
A lot of my friends utilise their skills to hunt down relic/data sites and anomalies within null sec, these can be a cash cow but more often than not it provides a little income for a reasonable risk. Wormholes provide a bit more of a incentive with C1 and C2's but any higher and you really need friends and a lot of ISK to start.
Whatever method of ISK making you choose I really recommend getting a second or third to help provide income when things markets are lean or there are issues preventing your primary income.