Sometimes you need to play nice with your opponent in a FFA and convince him that your his ally. And then when he least expects it, you backstab him with missile barrage and decimate his fleet. Well, here is a guide on how to do just that

1. Make a new account so people don't recognize you
2. Don't play any practice games so people are convinced you are a noob
3. Talk in all caps aka Huymac style so people don't think you have the balls to execute this grand strategy
4. Play vasari loyalist
5. Immediately after you enter the game, research feed and donate money to your nearest opponent.
6. Send envoys and establish trade networks 
7. Always do what he asks. After all, you are his ally right?
8. Whatever you do, DO NOT establish a peace treaty. Just a ceasefire. This is due to PT instituting a 5 minute delay for attacking when you break it.
9. Make sure your culture is the dominant one between you and your ally. Just tell him you got that part covered by yourself. After all, he does have more important things to worry about, like building a fleet
10. This is where the fun begins. Starbase all his planets under the guise of "protecting them". It doesn't hurt to break out the old minelayer either.
11. Whisper other enemies on the weak points of your "ally" and his defenses
12. When he rushes off to try to respond to enemy attacks, move your orkies in position of the most critical buildings.
13. Station your cap ships and titan on your friend's homeworld. Warn him of an imaginary Kostura cannon strike.
14. Right when his fleet seems to be victorious over the enemy, call off the ceasefire.
15. Watch all hell break lose as his income takes a nosedive and his fleet is destroyed by mines and starbases
16. Pat yourself on the back for a job well done. Repeat for other enemies.

I have won 95% of all FFA games this way, using this super secret strategy.