I think theres some "read first" threads on the for sale/trade forum. Give 'em a read. I basic rule of thumb I guess is try to conduct yourself with a basic degree of honor, do the right thing, and dont be an immature punk. IF you can handle that then i reckon youll be able to sell.
Oh yea, you have to include price on all your posts..
thats been my experience with MR, for the most part.