Tips for Vocalists:Please do not "cup" the base of the ball part of the microphone, it sure looks tough, but it sounds really horrible and causes feedback in the monitors. Sing directly into the microphone, please hold it within 2-3 inches of your mouth. If you sing quiet parts, get more on the mic, if you sing louder parts, back off a little. In-ear monitors will always tend to make a vocalist sing quieter, so please consider that. Also, please don't play the tambourine or other hand percussion directly into the mic, it can be heard with all the other open mics onstage :) And whatever you do, don't point the mic at the monitor! (you would be amazed the singers that do that, then learn quickly not to with a blast of feedback).

Tips for Guitarists: Please have your clean channel a little quieter than your distortion. Make sure your lead channel is at least 5db higher than the rest of your tones. Please be prepared to point your amps from the side of the stage (see stage layout diagram). This is done for stage volume reasons in the house. We can maintain a much more even mix by doing this. Who knows, you may always want to do this, you will find that you will hear yourself better without blasting out the people in the front row. Please have your guitars tuned and ready to go before your start time. Don't forget to bring cables, guitar stands, picks, power strips, amp power cables, etc...
If you play an Acoustic Guitar: It most certainly is better to have a pickup installed in the guitar or a guitar with a built-in pickup. If a mic is necessary for the guitar, it may be difficult to obtain a good sound in the house or give you more monitor volume if needed.

Tips for Bass Players: Please play the bass during line check the way you would play during your first song. A common problem is the bass player plays quiet during the line check, then all of a sudden comes in during the first song and blows everyone's head off. Check your direct output on your bass head, if you have high volume output issues or buzzing noises, do what you can to correct that before we discover it during a line check. Please be prepared to point your amps from the side of the stage (see stage layout diagram). This is done for stage volume reasons in the house. We can maintain a much more even mix by doing this. Please have your bass in tune before your start time.

Tips for Drummers: Please, oh please make sure you have a mic hole in the front of that kick drum, unless of course, you play for a jazz band. You will get a much better kick drum sound if I can put a mic in that thing! Please make sure your snare drum sounds nice and tight. I've heard far too many snare drums that sound horrible. Make that thing cut ! Please be sure to allow enough room for a sound guy to place mics on the tops of your toms and snare drum. I'll get you a killer drum sound if you can just do me those small favors :). Please have your drums set up and ready to go before the set change onstage. At the end of your set, please remove the drums from the riser in chunks, then dismantle the drumset on the dancefloor so that we may get the next drummer onstage setting up. 
If you play Electronic Drums: You may want to consider submixing your toms and cymbals to 2 channels stereo left-right, with separate outputs each for kick and snare (in other words, 4 channels that I can mix in the house). A common problem is not being able to mix the kick and snare properly in relation to the other drum sounds.

Tips for Keyboardists: If you play more than one keyboard, you may want to consider getting a submixer if you don't already own one. Run your keyboard to 2 channels stereo left right on your submixer for each keyboard, then send me a left and right output.  It can mean the difference of getting your keyboard in stereo or mono in the house if there are not enough d.i.'s or channels available. If your band is recording, it's definitely better to have a stereo mix on the keyboards.

Tips for Horn Players: If you don't already own one, a clip-on mic always sounds great and gives you more freedom to move around the stage. If you are a trumpet player, a mic shield is very effective to put on an SM57 on a mic stand.

Tips for the entire band: Try to minimize dead air in between songs. A common issue is, the band takes a minute in between songs to tune, change guitars, decide what song to play, etc.. With 15 songs in a set (for example), that's 14 minutes of wasted time (3 songs possibly), thus ending up in your band getting cut off at the end of the set due to time restriction. Please have your show timing in order so your set time doesn't get cut-off. (talking to crowd, handing out swag, etc. considered). Also, when you address the crowd, please speak loudly with clarity, not like you're speaking to others onstage. It sounds more like mumbling in the house if the person speaking is not addressing the crowd properly. The monitors onstage are at a good volume so you may think you're being heard out front, when if fact you may not be so well. Please respect the stage, and don't spit, vomit, spit fake blood, spill drinks etc.  in the lights, on the monitors, in the snake, or on the stage......and for crying out loud, please pick up your drinks when you're done ! They always gets spilled :(
Thank You :)

That's it ! Break a Leg ! :)

p.s.  NO MUSTANG SALLY !!!