Tear off a piece of wax paper and wipe the metal hanging rod in your closet. (One of mine is wood and it worked on it too.) This leaves a little film of wax and makes it oh-so-easy for your hangers, metal or plastic, to glide along. You can use a candle if you don't have wax paper handy.
I also tried this with drawers and it worked like a charm. Just pull the drawer out (again works on wood or metal) and wipe the rail in the cabinet as well as the actual drawer itself and it will slide in out out with no problems.
And that, my friend, is your Good Houskeeping tip of the day. You're welcome.