[dmm]

Eleven Ways to Help the AI (besides "cheats" like giving them unfair resource advantages, refusing to use certain weapons, abandoning all but one planet at startup, etc.):
1) Start with 10 good planets and high resources. Or 5 good planets and medium tech level. (AI is weakest in early game development.)
2) Don't make the galaxy too large. (AI doesn't expand as intelligently as humans.)
3) Make all AI players be aggressive xenophobic warmongers. (AI doesn't do diplomacy as well as humans.)
4) Don't choose any special racial techs for yourself.
5) Scramble the AI players (so you don't know what to expect when you first go to battle).
6) Turn off major disasters. (AIs don't know how to handle things like an impending supernova.)
7) Don't use galaxies that have lots of planet-less systems (which can stop AI expansion and agression).
8) Always use either strategic combat or automatic tactical combat. (This removes a huge advantage for human players over the AI, and prepares you for PBW.)
9) Use the option that gives everyone continuous full knowledge of every place they've ever explored. (This helps AI, which has no memory.)
10) Lower the setting that triggers Mega-Evil Empire (which causes all the AIs to ally with each other and gang up on you).
11) Set a strict limit on the amount of time you can spend on any one turn. Use a 3-minute egg timer. Once it runs out, you MUST end your turn. (Also a good rule for hot-seat play.)

When I do these things, the AI gives me a fun game. I still always win, but I like that.

If I want a real challenge, I can (additionally) use some of the cheats mentioned at the top. Role-playing is also quite fun and challenging. Examples:
1) Set MEE very low, and pretend to be an insane race intent on wiping out all other races. Never invade planets or capture ships; glass them. You might even consider blowing up their systems entirely to wipe out all traces of them.
2) Conversely, keep standard MEE, keep all AI players at standard settings, and pretend to be a dovish race that tries as hard as possible to avoid conflict (while trying to unite everyone under your peaceful rule). Never ever glass any colony, and concentrate on capturing or disabling enemy ships. You'll have to make and keep powerful allies to prevent triggering MEE.
3) Pretend to have a religious taboo against using warp points. Only give up this taboo when you can create your own.
4) Pretend to have limited authority. Use AI ministers to handle aspects of your empire over which you have no direct control.
5) Pretend that your empire has term limits that cause you to lose all political power for X years after serving 2X years as emperor. So alternate 24X turns of micromanagement with 12X turns of full minister control. People are SO fickle!
6) Play normally until you've triggered MEE, then switch sides. Now you are trying to rally the rag-tag rebels against the MEE! (Actually, I've always had MEE off when I did this. It is possible that, once MEE is triggered, the AIs would unite against the human player regardless of which empire he is playing. That would be a wacko bug!)