superconductors from colorado, planet denver to stuttgart, freiburg station and back from planet stuttgart with luxury food to planet denver.
4-points route;):
light arms from planet new london to omicron theta, freeport 9, there you buy food and go to omicron gamma planet crete, there you buy artifacts and go to cortez, planet curacao, there you buy vacationers (or tourists, I don't remember exactly) and go to planet new london -> this weird route was invented by me, and it has one advantage for sure - no pierats, no police, almost no attention, just need to be polite to Sairs.
Hm.
If you're into smuggling and trading with unlawfuls i could suggest that route:
Blood Diamonds from Dresden, Vogtland Base (Hessians) to Galileo, Pradua Base (Rogues) - 1913$ Profit/Cargounit
Pharmaceuticals from Galilo, Pradua Base (Rogues) to Galileo, Leiden Base (Lane Hackers) - 96$ Profit/Cargounit
Counterfeith Software from Leiden Base (Lane Hackers) to Omega 47, Casablanca Base (Hessians) - 2929$ Profit/Cargounit
Blackmarket Munitions from Omega 47, Casablanca Base (Hessians) to Dresden, Vogtland Base (Hessians) - 783$ Profit/Cargounit
However it's quite a long run and therefore not very profitable considering the time you need.
A quick safe route is Copper in Peurto rico to planet denver, and pharmaseuticals(fudge spelling) back.
Smelter to planet, planet back to first base in rico. Simple/short/legal.
Ilegal mine scrap in NL take to Crete, bring back artifacts.