how to get more sales through your website
You can spend a load of money on PPC marketing, bringing more visitors to your site.
You can spend a load of time (and probably money) on improving your search engine optimisation, such as link building to bring more visitors to your site.
Ironically, most companies would do best spending 60 minutes thinking about (and actioning) what visitors would PREFER to see when they get to your site. This strategy is not for you though. Go spend some money.
As little as possible. The less you spend on your website, the more money you have left over for biscuits.