For the most part trading will be enough whe you first start out. As in trading from starport to starport. I suggest trying to get a positive rep, although a getting a negative rep is quite fun. It pays off in the long run to be a good guy. After you get trading down pat and have made around a million dollars you should attempt to start a colony.They cost a lot to start up, but they can make you upwards of $100 000 per hour once it has around a 20 - 25k population. But you MUST watch over your colony and place laser turrets, mines and get the solar cannon going at a decent power because a lot of players just wander the galaxy looking for colonys to "cap". (Used as a short of capture)
But anyways. Have fun and good luck.