Achieving a full bodied, powerful live guitar tone isn't easy. There are a lot of factors that come into play to get things sounding just right in the mix. One area that I think is responsible for a lot of hurt, more so than any other aspect is bad EQing. This is a problem that spans all genres and styles, and is something I have seen bands at all levels fall victim to. It doesn't matter how good you are, if your live show sounds awful then it detracts from the enjoyment of the gig tremendously, worse still you could actually be doing serious damage to your ears in the process.
All In The MidsGetting your guitar sounding right as a standalone instrument is one thing, making it cut through the mix and harmonise with other elements is quite another. The secret? It's all in the mids. Why compete with bass and drums for low end? They have that covered. Vocals and cymbals have the highs. The guitars place should be firmly in the mid range. That is a very simplified explanation but I think it generally holds true.
Playing by yourself you will be tempted to cut the mids. It will generally sound more pleasing to your ears, but keep these settings in the mix and your sound will get lost. What do you do to compensate? Crank up the volume of course! No, no no no. That is where so many go so wrong. You might be able to hear yourself now but you may have just raised your bass and treble to dangerous volumes and thrown off the sound of the mix as a whole.
The solution? Give those middle frequencies some love. Your sound will be much more balanced without needing excessive volume, it will drastically reduce feedback and gives the sound engineer a lot more room to work with. More and more guitarists are starting to realise the importance of the mid range, but some don't truly understand it. Anything from around 500Hz to 4kHz can be considered 'the mid range' generally speaking. Anything below is low end and anything above, high.
Play with your band and get someone to adjust your bass, treble, mid, gain and volume until you hit the sweet spot. You'll know when you do as everything will sound balanced and luscious, with no feedback when you stop playing. I'd love to just give you some magic amp and equalizer settings and be done with it, but in reality all gear is different! You'll have to do some of your own experimenting and fiddling to get it just right.