My fave: Crassworms at Pax, sell at Ohm. Buy Medical, sell at Telnan. Buy Equipment, sell at Pax. Repeat. (That's what I recall right now-game's not open.)
Start with freighters, upgrade to Miranu Heavy Freighters when you have about 3 million credits. You can make enought money in an hour of real-time play to allow you to concentrate on missions and not have to worry about whether you can actually afford that new UE Cruiser/Igazdra/whatever.
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"Mary had a little lamb
She tied it to a pylon
10 000 volts shot up its a$$
And turned its wool to nylon"