First of, the reason for soundchecks. Imo soundchecks are there for the monitor levels, equipment check (i.e. all amplifiers microphones and cables etc are working) and to agree levels with the sound op, if there is one. The actual sound out front doesn't matter so much so don't get hung up on it, it can change dramatically when the venues got a few bodies in it. Trust the sound op to know the room. Now to the actual soundcheck> The standard way is to start with drums Kick ( bass drum, it gets too confusing if you call it that though) snare, hats then the toms on order. The drummer should hit the drum at gigging velocity leaving enough time for the sound to decay before hitting again, repeat until told to stop then move onto the next one. Next is normally bass, play a reasonably slow riff ,covering all of the strings preferably, until you're told to stop. Guitars next (in my world anyway), get you're clean and distorted sounds balanced up (follow the engineers instructions on this once YOU'VE got them in the right ballpark) Keyboards, acoustics etc are normally dealt with next but I'll skip them. Then comes vocals. Preferably sing into the mic rather than shyly whispering "check one two" into the mic. Now monitors (the engineer will most likely have done some of this already). Your band should have a well balanced sound without monitors, you should be able to hear everyone, apart from maybe the guy on the other side of the stage. That should make it easy enough to get the vocals up enough and all the 'bleed' through other mics doesn't fuck with the sound too much. Keep your monitors simple on a small stage, the more sound knocking about up there the more potential phasing problems and just sheer unwanted crap flying into the mics. Identify what you work from at practice and make sure you can hear it. I've probably missed out tons of stuff here but if it's your first gig, get there in enough time to watch other bands soundcheck (if you're sharing drums with another band you'll be spared the evils of a drum soundcheck for your band, lucky people).