First i need to know what your website main product. If what you are selling are not interesting for the customers, i don't think good SEO could bring you more buyers. I can give you advice on your website content,including items,promotion,website style in a consultant's view.
Second, Use SEO technology to optimize your website.
Third, Advertise your website if you have enough budget through GoogleAds,Facebook, which depends on your product features.
Good luck with your website!