IMHO...... Don't put your arms out to catch yourself. You will get hurt worse trying to break the fall with arms and hands. Don't land on just your shoulder either. The shoulder should be your final resting place unless you want to continue the role to your back.

Keep your hands on the bars and let your lower leg touch first sort of continue the roll up your body like they used to teach parachutists when round canopies were the thing. When you get over the scare and novelty, you can wind up on your back with the bike above you and just pedal away to divert some of the embarrassment away with humor.

I've never been hurt falling this way, though sometimes you get an abrasion that stings for a few days.