From StrategyWiki, the free strategy guide and walkthrough wiki

There are several ways to make money. First, you'll probably be tempted to find a resource field and strip-mine it. This cannot be stressed enough, never ever mine a field below 300. The fields regenerate on a basis of what is already there. If you drop the field below 300 you will be stifling future profitability of new players.

The best thing you can do is spend a little time in your home sector doing a F-W-E run. Learn where the monsters are, and avoid them in your Sabre. You will have plenty of time to kill monsters. You need to save up for some travel.

If you have any friends already in the game, find out where they are and help their economy as much as you are able to. If you do not know anyone in the game, it might be wise for you to consider joining an alliance.

Generally, you want to be getting Food and Water from class M planets and selling it at a star base where you buy Energy and take that back to that class M planet. You will not be making a ton of money doing this, but you will be able to make some money and gain some XP. Once you get enough credits to buy a new ship, you can start doing some missions - these will really help you get credits.

Possibly the most important part of earning money is to always have enough fuel. This is something a lot of new people overlook, but if you get caught in open space with no fuel, you will most likely be attacked or will waste a lot of AP's getting home.

--(This wiki should include specific trade routes for each of the home planets)--