Be up on your terms: abduction, adduction, extension, flexion, etc, etc
Know your precautions for movement (ie what is a big no no for post op hips?)
Know your facility's standards -- when can the post up knees get up? how long does the CPM stay on? what post op day does the foley come out? how many hours do you keep the heels off the bed? HINT a lot of the docs have a standard order sheet. Take a copy and learn it. Do they have a cheat sheet on what kind of dressings the doc likes? For ex, dont change Dr. X's post op for the first time - he will. Dr. Y expects you to have it done before he rounds on post op day 2, etc, etc.
Know thy blood thinners. Heparin. Lovenox. Coumadin. the Labs INR, PT.