How do I workout just one side of my buttucks? The reason being, for some reason my left side is being worked out more then the right and I want to try and even it out. I tried to just work out the right side slightly longer then the left but that doesn't help.
Any suggestions?
Also, I find that my left cheek keeps itself clenched even when working out the right side... which is most likely the reason why its being worked out double time... does this happen to anyone else and if so, what did you do?

I'd see a physio, check if there is something going on that you should know about.

Single leg stiffleg deadlifts are a great way to work one buttock.