Home Depot paint department sales a 3 foot wide
by 12 inch deep sheild with a handle. this is a lot better than trying to mess with homemade cardboard shields. also, have a 4 inch brush in your hip pocket to smooth out any excess paint and prevent runs. Dont try to get maximum coverage with the first pass of the gun. always start at the top and work down, keep gun @12 inches away from surface and overlap passes to get good coverage. always have the gun in motion when you pull the trigger, and continue motion after release of trigger, or you will have a big run immediately. If you do not finish the first day, put the gun in a bucket of water overnight to prevent a clogged gun.