Well...
First you need to decide whether your account is a pure/skiller, or a main. Then go to the black market section of these forums, find the right category and make a new thread.
Make sure you take pictures of the stats, best items, and the log in screen. This ensures that you do not have recoveries, or a bank pin.
Using an Official MM, or highly trusted brings in more buyers. Also a reasonable price helps whether it be RSGP or irl money.
Hope this helps.