Bench dips can create shoulder problems if not done correctly.
Two things when doing bench dips:
#1. Keep your abs tight, stick your chest out and keep your body close to the bench. Your butt should almost be scraping the bench. Being to far away from the bench will cause shoulder strain.
#2. Your elbows should not go higher than your shoulders (example not shown). Going to low will put unnecessary strain on the shoulders. Go until your upper arms are parallel to the floor.
For beginners, keep your feet on the floor. Straighten your legs for more of a challenge.
Advanced, add weight plates to your lap to increase resistance.