Water confidence and being quite comfortable swimming in moving water can help you avoid injuries.  Let's assume you fell out of your boat and are heading quickly towards a large wave train.  Would you panic in the wave train and waste energy trying to swim to shore or head for a small rock in the middle?  That might not be advisable, you need to relax and set-up your defensive swimming posture.  Calmly survey your surroundings, is there a nice sized eddy within easy reach?  If so, rotate the body to the aggressive swim position and high-tail it to the safe eddy.  If not, relax and enjoy the ride with minor course corrections to avoid rocks, strainers, and other safety hazards.  By conserving your strength, it will be there when you need it.

Another safety concern is when a rescue is in progress.  Survey, Think, Then Act!  Be honest with yourself, if the victim is too difficult for you to assist safely - don't try.  Most rescues are a group effort, think of other actions you can perform to help out.  Novices are probably not the best persons to implement boat based rescues.  On the other hand, many seasoned boaters forget to set safety below the rapid or warn off others from above.  These are perfect jobs for novice boaters - safe and exceptionally helpful.