oldsmellhound
Think everyone will tell you about the muzzle mitt, either regular store bought black rubber boots or the cheaper Wal-Mart finger cots... I do prefer the black mitts the rubber is slightly thicker and stronger.
The other area I try to protect is the nipple area. Most #11s probably fit tight enough you do not have to worry about it much - but I still do - so i wrap mine with plastic wrap - you know that packageing wrap that is a bit sticky and come in a roll. It really is just like saran(sp) wrap. I roll up several feet of it on a small diameter wood dowel and carry it with me. When I think I need to I pull the hammer back and wrap the nipple area with a couple of wraps. You do not need to remove it to shoot just pull the hammer back and let it drop. It does blow a decent hole in your wrap when it goes off but it makes it really to get off.
Here is a pic... It also shows a commercial #11 cap wrap but I can not find these anymore - but they were really good.