If you've reached San Fierro yet, you'll have no doubt come across Zero's mission "Supply Lines" (or, maybe not if you're still having trouble with "Air Raid"). It is, without a doubt, one of the toughest missions in the game. The Untouchable has written a fantastic guide to passing this mission, one that will surely be of help to you if you're still having problems. Be sure to check it out at our forum.
Expect many updates in the coming weeks, along with many new guides and maps to help you with San Andreas. As always, we are open to suggestions on how to improve the site.