Well after skimming through the thread ive found the most popular, helpful and most profitable runs.
I see that many people comment on minning niobium for great credits.
Also a run with niobium from Tau-37, Freeport ten to New york, Baltimore Shipyard, thats $1889 profit on each piece, also with this run you can then take neon ($1537 per unit profit) back to Tau-37 from planet manhattan, Freeport 10 and then niobium back to New york and so on.
Then theres the BIG run posted that can potentially give you the cash:
Barrier Gate (Coronado) Black Market Munitions (3110400)->
Fort McMurray (Alberta) H-Fuel (1688400)->
Kingsington Shipping Platform (New London) Mini Machinery (2422800)->
Toronto Station (Ontario) Platinum (6678000)->
Leipzig Station (Dresden) High Temperature Alloy (5425200)->
Newark Station (New York) Robotic Components (2260800)->
Fort Severn (Ontario) H-Fuel (1774800)->
Arranmore (Dublin) Gold (6292800)->
Narita Outpost (New Tokyo) Mining Machinery (2430000)->
Falkland Base (Tau-37) Niobium (5904000)->
Planet Manhatten (New York) Neon (4399200)->
Planet Kyushu (Kyushu) Light Arms (3837600)->
Cape Wrath (Newcastle) Cardamine (4291200)->
Buffalo (New York) Blood Diamonds (2318400)->
Pauda Base (Galileo) Counterfiet Software (9104400)->
Solarius Station (Omega 11) Diamonds (4892400)->
Scarborough Station (New Castle) Super Alloy (4201200)->
Yokohama Shipyard (New Tokyo) Engine Components (4676400)->
Baltimore Shipyard (New York) H-Fuel (1101600)->
Alcatraz Depot (California) Light Arms (500400)->
Barrier Gate (Coronado)
--- Then Repeat ---
If followed correctly this run has the potential to earn large amounts.
Also remember, the bigger your cargo the bigger the profit, im unsure of the cargo that person used above but the main fact is that it works and you can do it.