When I meet a Minor Race I'll give them all my tech for cash. I'm guessing that since they are a "Minor Race" they wont turn it against me. I can pound them to dust later if needed.
Also, when I trade tech with a player I'll set up the trade that he likes (Text is green) then go for some cash on top of the trade. I'll try to get every last credit from him!
I'm still getting my butt kicked against the AI but thought I would share what I have tried so far.