I don't wear neckties very often, and unlike cut-offs, they don't just zip and button in the front. So I tend to forget what to do with them.
If you're like me, you might find the following chart handy. Some folks selling ties from a table in the MIT Student Center were handing out copies several years ago.
The directions are also available for each individiual knot. The chart shows how to tie a Windsor knot, a Half-Windsor, a Four-in-Hand, and the classy bow tie. (Each individual GIF is about 50kb.)
I hope this is as handy for you as it is for me.