Here's a tip that's more effective against the AI than multiplayer: use missles. The AI, at least on stock, never uses point-defense that I've seen. Also, AI races use only one type of weapon when possible. For example, the Norak only use CSMs, which allows you to defeat an entire fleet with a handful of fighters. This is also a hint to start researching point-defense
Many races like to use direct-fire weapons, however, like the Phong, who use Shard Cannons. There, you can exploit the AIs weakness of little to no PDC, and use a bunch of missle boats with strategy set to max range. That way, you can keep out of range of those pesky anti-proton beams and the like, while still being able to attack your opponent.
Lastly, if you feel the need to gain more advantage over the AI, use tactical(I think that's the name for manual combat... I always get the two confused) combat. Once you get the hang of tactical combat, you can win even when you're vastly outnumbered.