Other than that I think it's just basic RTS. You should try air units against the AI first before playing on Friday as they are a bit obnoxious to control. Best civ I don't remember exactly either but there was one that has better workers, which of course is imba, and one that can upgrade units cheaply. Don't remember the exact name, but they are an all purpose unit that is upgradable through all ages up to future tech. Best tech / upgrade choice are the riflemen in mid ages / renaissance. Might be fun against the AI though I guess.

Playing beyond WW1 is stupid in 1v1/FFA because of how powerful nukes are. One guy going templar forces everyone to build defensive temples basically. So, 2 or 3 stone age templar can take out an entire modern age air fleet with well placed volcanoes next to the air fields (yes, I had that happen and yes, I was the templar terrorist). 1 or 2 volcanos can obliterate an entire base regardless off what age you are in. They can cast plague (works pretty much like in BW if I remember correctly), earthquake (stupid) and volcano. You can build them at all tech ages and they are equally powerful on all ages. Other than that, from what I recall (more applicable to 1v1/FFA): Just set up defenses and tech and let the AI run units into defenses. Playing against the AI should be pretty boring though.

Empire earth 1 vs 2