Chevy cavalier running down battery?

I know this has been posted but I need some specifics. Not much of an electrician, just a mechanic. My friend has a chevy cavalier that keeps running down the battery. Belt is tight, altenator checked good on the stand. How do I SPECIFICALLY check for problems. What tools do I need? How EXACTLY do I check for a DRAW or leakage of battery power. PLEASE HELP!!! The pros want your unborn child and you're left testical to fix or trouble shoot