Some tips to keep your bars healthy:

Tip One: Tighten your bars often.
Tip Two: Sometimes take them off the step and clean up the contact of the stem.
Tip Three: Tighten all the bolts evenly.
Tip Four: Get some bar end protectors if you think you need them. They do save your bars a lot!
Tip Five: If you are cutting down your bars, then do it with caution and care. Cut them evenly, and file off the rough ends, otherwise they cut the grips.