It all depends on what you are selling and how. If its a product its easier to sell just use reasonable pricing and pictures with your username and always mention and use escrow while selling people will buy if they get interested.As far as its a service based company its hard to win trust over cuz firstly the website will ask for upfront payment that too in btc (non-reversible) to avail the services offering so try to advertise or maybe get yourself listed in any newspaper and also provide full and correct information about yourself on the website. The best will be offer your service to few of the high ranked people on this forum for free let them test your service and be a proof for you !!! Thanks and good luck