Trade.
Agricultural (farms) grows things and produces from organics mainly. uses biowaste from everywhere. Trades to everywhere.
Refinery (quarries ish)- uses agricultural products like food and clothes, refines ores into mineral, uses technology and equipment. Trades mainly up to Industrial.
Industrial (factories) - uses ores to make machines and equipment mainly. Trades up and down.
High Tech (Computer factories) - use equipment and machines to make tech for all. Trades to all but tourist & industrial mainly.
Tourist - no production apart from by organic products of human tourists. Buys consumer stuff mainly.
Military - usual food needed but also some military fabrics at vast profits sometimes (10K plus per ton on right route). Produces amrs and weapons mainly, often illegal elsewhere.
Most of them do trade up and down and can sell to all or buy from all pretty much so dont panic just buy whats cheap and see what you can sell.
Market has a Compare button to left. Can set to 'Galactic Average' and see whats most profitable. If doing this buy a range as dont want to be stuck with one cargo full of one item you cant sell. can compare to other market but its not working properly. What you can do is type the name of the system in and choose the market from there or go to selected ones which takes ages going through all the FCs. Must have visited the system within 24hrs to have data available or can buy from GalMap directly for that system (if its not bugged, have only done that once to see how it worked long ago).
Buy low sell high or for a profit and buy something else. using Average and picking a range you wont go far wrong and soon learn which are easier to offload (Meds, consumer tech, food & drink, legal drugs). At an Agricultural if in doubt buy Tea, its always a failsafe profit. Be careful with Biowaste, nobody wants it but Agricultural.
Then theres system and faction states. Boom increases profit at both ends, lower buying price higher selling price while it lasts. The rest? Id rather explain the rules of Quidditch than begin to try and understand them but gl to you, trade is a lot of fun however you play it, back and forth between 2 systems or just pot luck and jump and make a profit, or trade as you go somewhere never flying empty on the way
