Tips on live sound setup.

[TeslaRect5150]

I've been asked to be the "soundman" for a local band. They mostly do cover songs and play small venues, like a bar/casino band. They need help setting up and need someone with "good ears" to get their levels right during the gig. They have been struggling to do it all themselves. I want to do the best job I can do, but have little to no experience doing this sort of thing. I'm willing to work my ass off to learn as much as I can and make this band sound as great/pleasant as possible for the audience.
I'm asking for some help here. I've read up on a few things, but am wondering if any of the members here can give me any hints on running/setting up a live sound situation. I figure the best way to learn is to just dive in and go for it. Try my best is all I can do.
If anyone has any experience that is willing to give me some tips and tricks to this game....I would be very thankful! 
 

Peace and Thank you to all that can help,
-Aaron