I submitted the sitemap for one of my sites using Google Webmaster tools AFTER having built a few links.  Turned out to be a bad move as Google then seemed to drop all of the original inbound links plus my site from SERPS for a few days, then my site re-appeared without the inbound links.  It was all a bit strange and damn frustrating.
My tip is to use Gumtree as mentioned earlier, seems to get new sites indexed fairly quickly.