To remove the membrane from the rack take a a blunt knife (like a butter or table knife) and slip it under the membrane along the end bone. Move the knife around a little to loosen the membrane so you can get a good grip on it. The membrane is a slippery skin, so grab it with a paper towel and you shouldn't have any trouble lifting it right off. With a little practice you will be doing this so quick and easily that you won't think twice about it.
With the membrane off, inspect the rack and remove any loose meat. This will only dry out on the grill so you don't want it on there. What you want is a good, clean rack of ribs that is square and even. If you are using spareribs you might need to so a little more trimming.