Make a point of searching inside discarded containers as there is a chance that you will find gold which can then be sold on the Blackmarket.
Easy Cargo Money
If you make a note of what economy each space station specialises in you can purchase that cargo at stations where the commodity is cheaper and then travel to the space station where it is in demand and sell it for a higher price.
Take note of the economy of every space station you encounter. Each colony specializes in a particular commodity, and will buy specific cargo at higher prices. Purchase extra cargo at stations where the commodity is cheaper, then travel to stations where that product is in higher demand. Enter a Low-Intensity Combat Zone and scan it for NPCs that are wanted or from an enemy faction, all while avoiding other players. Destroy lone ships to earn money. Search for discarded containers, especially those that contain gold that can be sold on the Blackmarket.