Don't over tighten and always lube the threads.

The former is uber hard skillz to learn. I use the flex of my hex wrench. But you know, some people tighten the bolts so hard the handlebar is left deformed. (and evidently bolts never failed during the use by those users as no trace of slippage detectable) But you shouldn't risk it when you don't need to. If you feel your stem is too trashed, replace it.

I try to get stems with bigger bolts like 5-6mm hex. I get more feel of threads. I know some stems use 4mm, but the hex wrenches at that size (or smaller) start to twist enough that I can't feel the bolts seizing sometimes. Totally uncool.

Stripping threads feels like sudden release of tension. You won't "hear" it. You will feel it release. I am lucky I never had bolts snap in the middle tho.