Don't do it. Make sure you really don't want it anymore. Don't let garage sale fever take you over. If you still love and use it, don't sell it. You'll be sad later.
Big items command big price tags, which translates into a bigger pile of cash at the end of the day.
Check the value of your items first. You might be giving away a real treasure for much less than it is worth, so do your homework. Have it appraised or read up on it at the library or on the Web. You might have better luck auctioning it on eBay . Skip the unmentionables.