Any tips on how to prevent or reduce them?  Are gloves better than tabs?  Is there a best way to grip the string to reduce them?

The best way is probably to distribute the pressure evenly. I never used a glove or a tab, and my bow pulls 70#. Must admit though, that if I haven't shot for some time, it will hurt a little bit in the start. Sometimes I put on a strip of sports tape on the ring finger, to prevent the worst.

I shoot 50 # bows and i have been using he same glove that i first started shooting in.. Ive never had a single callus from shooting (bike riding is a whole nother story lol) I do get sore in the crease in my fingers and my ring finger pretty much always goes numb. But no calluses!!

I just use a glove and haven't really had a problem.  Even weight distribution, as mentioned previously, probably helps quite a bit.
S.

I shoot bare fingers. Gloves and tabs mess me up bad for some reason. I found hooking the string deep in your finger grooves helps eliminate boo-boo's

I have the issues of callouses on the pinky side of my ring finger.  I shoot split finger with a tab...have never really liked a glove, I don't get the feel for the string as well.  The only thing I have found that helps but doesn't cure, is make sure your draw elbow is not too high and that you are  not twisting the string with your ring finger.  Like I said, it helps, but doesn't cure.

Assuming  they arent cracked and bleeding,as they sometimes do, be proud of your callouses. they show that you use your hands for more than just pushing the button on the TV remote.

I have a permanent (at least up to this point) dark callous on my ring finger.  It's kinda ugly and looks like I have dirt there.  Funny though, when I'm not hunting or shooting sometimes I look down at it and get a good feeling about things and life in general.