trade, trade and more trading in both lawful and unlawful systems. Its the only way to get the credits needed to supply the maintence of ships and the consent growth of a player. Long routs are not always the best but usually make the most, it really all depends on the time and profit margin.
you might know me as the Cowboy_Bebop ill trade for hours on end only to fuel the demands of a growing fleet. In one day (about 9 hours stright) i made about 120 mill. if you have the time and patience any amount is in reach.