Take everything out. Try everything on, one by one. Have a friend with you to help you decide to "keep" "toss" or put in the "undecided" pile.
Take a digital photo of all the undecided items - photos often can help you see yourself better than a mirror!
If you still have lots of undecided items left over, bag or box them all up. It helps to organize tops vs skirts vs pants when you do this. Then stash them away someplace dry (not the basement).
Give it a year. If you miss something, go ahead and pull it back out. At the end of the year, if you haven't missed it, you won't ever, and you can safely toss the entire bag without looking in it again.
If you don't trust yourself not to look in it one last time... then have someone else toss it for you.
Lessons curtesy of flylady.net.... for anyone who wants to learn how to declutter anything...