This has been asked and answered many times. Might be best if you do a search, too.
I've had pretty good luck on Ebay, but that's me. There are dozens of websites that will list your domain name for sale. I would suggest that you, at least, put a page up on the domain name showing that it is for sale. You can also post your name for sale at dnforum.com in the appropriate category.
Good luck!