im coming at this thread with a totally different perspective than others, so here goes.
1. dont play rock music. its tasteless.

just kidding
2. be able to adapt to problems or deficiencies. ive never had sound problems on stage, or been thrown off by problems in FOH/monitorworld. maybe im just good.
on a more serious note:
i play in clubs in a major US market. bringing your own PA is a laughable notion for us. not even on the radar. this is typical. you get 10 minutes to set up your gear, quick hey-hey...or sometimes a soundcheck before the doors open. so what i say, is coming from that stand point, not the "we play in the sticks and use our own PA and soundcheck for an hour" standpoint. also, i play in an indie-electro type band. we have a laptop running ableton drums, and sequences...not an ipod. we run bass direct and guitar direct and just hand the soundman a snake with all the stuff labeled on it. soundmen love us. its easier for them to mix, they dont have to deal with stage bleed, this makes you sound a lot cleaner in the room when everything is coming from a single source instead of two.
if where youre playing sounds bad, because of PA or soundman or acoustics or whatever...it dosnt matter what you do, it will sound bad. if you play a place with good PA, soundman and acoustics...its up to you to sound good.
not having a drummer makes me happy. not having an amp on stage makes me happy. all of the above makes the soundman happy. never had problem one, and its quick, legit, clean, and good.
and if anyone in the audience ever comes up to us after a show and says "you know running everything direct sounds bad, you should have amps on stage" i will kiss all your butts on the courthouse steps. you guys know im right.
it all comes down to the soundguy whether you have an amp on stage or not. obviously if you have a drummer and rehearse in a regular ol rehersal room ok, you need an amp.
also, somebody said singer should get his own mic...in my experience, this is bad and causes soundmen to bitch because they already have thier stages/boards set-up for their own sm58.