SC belt squeeling

Well its been raining here for the last week and when I really give it some gas the belts squeel. It only squeels at high rpm's when the SC is really kicking in. I have had the shop tighten it once since the new belt was put on, and it worked fine for a couple days but now its squeeling again. I need to know how to do this myself so I don't need to keep going to the shop. I asked if I could watch them tighten it but due to insurance reasons I couldn't go back in the shop while they worked on it. I think the belt is pretty tight is there anything else besides tightening the belt that might be helpful? And if not, how do I tighten the belt? And how can I tell if it is tight enough?

Oil it up!;Dr;

Somewhere on the site is a post on checking tension. Hope it's not TOO tight or a S/C or tensioner or idler bearing problem. Are you sure which belt is squeeling? Can you isolate the noise by applying belt dressing (a temporary fix) to one belt, test, then apply to other belt? .Try a new belt? How many miles on the S/C?