I've played 3 a long long time ago, and 4 and 5 more recently. I am not sure but I think HAM and Victus and some others might be playing civ when they are hanging out in the poker channel =] unless I got my wires crossed.
WRT to tips... it really depends on your gamestyle... whether you want to attack another civ early on using an aggressive nation but crippling yourself financially in the process, or if you want to guarantee longevity by being creative and more technologically advanced. Cos I'm used to the recent Civ's, I'll get out my Civ III at some point in the next week to refresh myself with what features it has =]
Will report back...
~Z