One I put on another thread, but its more appropriate here.
Use Minor Races as a free tech source. They tend to go for non yellows, and in the main go for trade and military. Whilst keeping some low value ships around as tokens to ward off crys of "pay me dosh", concentrate on yellows etc, not military, initially, and get a the invasion techs / Ti(thingy)Quan whatever its called.... for soldier bonus. Get good diplomatic techs to have a better level than the minors (more efficient to trade that way)
At the point you want to "get going", click on the nearest minor, look at what weapons he has, build defence for it, one medium fighter using weapons he has not defended for, two transports (one will probably do it with the soldier bonuses), and head on over to the minor. position the "fleet" (all three of them!) within striking range, and open up negotiation for every tech and cash they have. By this stage they have been been getting weapons techs, and if you dont do this too early lots of cash from their tradingso you get lots of freebies.
Trade everything you have - the lot - if necessary (dont give them soldier bonus techs). When you've drained the lot, say "Ta", pull out and on the same turn attack (that way he has no chance to trade your techs you just traded to him, to others) and take the Planet. Then on the same turn sell/trade the lower techs to any other AI who doesnt have them.
You kill him him one turn, get lots of freebie techs, all his cash, resell a lot for more cash, catch up and often leap ahead on military techs, get back all the cash he earned from your trading with him, and get a good influence bonus - all for for free
You have to plan ahead for this, but its easy to do. Later for desert, use the other minor AIs you didnt hit for this, as a culture bomb see (reply 15). I am a fan of the maximum Minors option .....
Its a Dog eat Dog Galaxy