Posting on forums is one of the cheapest and fastest ways in which you can advertise your affiliate products on the Internet. However, in order to do this successfully, you must do a number of things with care. You cannot simply start a thread which contains your affiliate link straight away. You will almost definitely get banned from that forum board and you certainly won't get any sales from it.
The general procedure involves making multiple posts on a forum board before you even setup a signature...