Heh. At the risk of sounding like I'm tooting my own horn, I'd guess I'm *the* source for MP strategy guides.... or at the very least I've written more than others. Here's a few good ones - my favorites at any rate - which should be a pretty good primer:
(Many of these were on the old PTW forum but I can't find them since that forum went defunct. I would repost them here on my favorite home, Apolyton, but honestly, the Conquests forum is too SP-centric, and they aren't really appropo for the Strategy folks.)
I don't know if I'm allowed to post links off-site? If not, I'll definitely repost them in this forum - not trying to slight Apolyton, as it's definitely my favorite site.
Conquering The New World of Civ 3, or, An Examination of the Civilizations At The Time Of Conquests For Multiplayer
http://civ3players.proboards2.com/in...num=1070338821
Don't Blink, and other tips for MP Elimination Games
http://civ3players.proboards2.com/in...num=1052683902
SIEGE! The Art of Taking and Defending Cities
http://civ3players.proboards2.com/in...num=1052682107
Pointy End in the Other Fellow - Warmonger in MP
http://civ3players.proboards2.com/in...num=1052682335
Beating the No-Iron Blues and other MP Problems
http://civ3players.proboards2.com/in...num=1052683530
Thwarting the Pillagers (By Sperricles)
http://civ3players.proboards2.com/in...num=1052682828
...and my newest article that I'm rather proud of:
Playing the Metagame - Overarching Civ3 Strategies
http://civ3players.proboards2.com/in...num=1074303641
That's a pretty wide-ranging set of articles that should help you make the difficult transition from SP to MP.