Managing UAT / Defect and Bug raising

Question

I'm looking for assistance in figuring out the best approach to managing User Acceptance Testing (UAT) and how users raise defects/bugs - I've been in the situation before of having to deal with a free for all in that every small error is raised as a bug which takes valuable time from actual bug fix whilst I sift through lots of invalid defects/bugs.

Don't get me wrong, i'm not trying to short shift users by saying "not a defect" but trying to make the process smoother so that things get fixed.