Yes, buy and use a Kriket II tension gauge which you can pick up at any NAPA store IF the clerk knows how to look it up in th book. I posted the NAPA part number somtiem in the past year on here.
I have found generally a belt squeel is caused by too little tension or bad contact with the pulley making the noise.
I change the idle pulley on my 88 XJ 2 years ago and the belt would squeek first thing when I pulled out of the parking lot. Once the paint was worn off no more squeek.
I also noticed once you belt starts to squeek it will be glazed which makes it easier to slip. My advice is to install a good belt like a Good year which you can pick up at Autozone for $30. The groove are cross cut on an angle to make less noise. Remove your current belt, wipe down all the pullies to make sure no junk on them then install the new belt and tension with the kirket II. I installed a new belt this spring and it doing just fine, no noise, no glazing.
The key to avoiding belt sqeek is a proper tension belt and clean pullies. Also if the belt had make squeeks in the past it will again since it is glazed.
While you have the belt off check all the rotating comporents for smooth operation, if they turn rought then change them. One last thing if your fan clutch is over 5 years old then spend the extra time and replace it while you have the belt off, it much easier to get to all 4 nuts. You can turn the fan clutch to gain access, if the belt installed the 4th nut a pain to get to .