Another element to live sound that needs checked is monitor volume levels. Unfortunately for the United States the past few years have been riddled with celebrity musicians messing up our national anthem on live television. The most recent of these incidents happened today when The Fray sang an acoustic version at the NCAA Final Four game in New Orleans. After watching this my initial thought was that someone just didn't know what they were playing and ill-preparedness caused a horrid performance. However, after reviewing the video two more times I realized something. What didn't sound right in the third chord every time that was played was indeed the lead guitar, which was odd because he sounded fine in the intro. That's when it struck me to watch his fingering for the beginning when it sounded right and then watch them for the rest of the song. The very second the rhythm guitar comes in he appears almost unable to hear himself, and begins playing that last set of notes one half step above where they should be played. Yes, the entire song could have been fixed if he moved his last fingering down one fret every time he played it.
My conclusion here: A bad sound check. It's no secret that many LIVE performances at festivals, football games, and other such appearances where bands may only have a limited time to play get a rushed job at sound setup. I honestly believe if the lead guitarist in this case was able to hear himself well that he would NOT have kept playing wrong notes every single time it came to that third chord, but would have realized it was him and fixed it. After all, he was only a half step away from the right ones!!!
I've experienced this rushed sound job firsthand too many times and learned some tricks to getting around it. First, always be sure you can hear yourself. You don't know if you're playing the wrong notes if you can't hear what you are playing. It sounds selfish but as a musician you are in charge of your instrument. Don't feel bad asking the sound engineer to turn you up just a little bit more so you hear clearly what you are playing. Yes they'll make a joke about guitarists always needing to hear themselves too loud, but better that than not at all.
Next, be sure you can hear the other key elements of the group well too. If you're a rock band then you probably need a good strong kick drum, hi-hat, and snare in your monitor as well as solid bass and vocals. Make sure your guitar bleeds through these enough you're the prominent instrument in your monitor mix though if you can.
So steps one and two take care of you and others. But what if you only have one monitor mix? Position your amp, halfstack, or whatever kind of amplified speakers you have in such a way that you can hear it onstage where you are standing. Then ask the sound engineer to give you a mix similar to how the main speakers sound. You'll all be able to hear one another but still hear yourself when you need to.
Lastly, and certainly not least, on the fly mixing. Many festivals and competitions have the stage area backlined, this means amps are set in front of amps with the first bands setup in front and each following band setup behind the previous one to perform. A band will play and take their gear, leaving the next one's gear in position and ready to play. This is typical of large festivals with large acts playing. Another trick sound engineers use is for one band to setup while another is tearing down and then mix on the fly. Whether you're backlined or asked to setup right before you play, you will at some point face the dilemma of not being sound checked and having to play. Two tricks here. When the sound guy asks if you're ready to begin, you play your instrument or sing into your mic one at a time quickly to determine if he has you in the monitors or not. If you sound decently loud enough then go with it and he will mix you well while you play. Secondly if you need something while you're performing to be turned up or down in your monitor let the sound guy know! Get his attention in a not so obvious way (eye contact followed by pointing at what needs changing). He will then motion for you to say what you want. Here's what you do. If you're guitar is too quiet in your monitor, simply point at the guitar, point at the monitor, and then point up. He will know what you mean. Then give him a nod or another sign when it's loud enough.
All of this is to help you, the musician, and everyone coming to your show. Always sound check if possible! Always be sure you're loud enough in your mix so that what happened to the Fray doesn't happen to you! And most importantly, practice. Practicing makes playing second nature and reduces careless mistakes onstage. It wont actually make you perfect, however, the crowd may think otherwise. Thanks again, hope this helps!
To quote AC/DC, "We roll tonight, till the guitar bite... For those about to rock, we salute you." Rock on friends, and never stop.