SEO (onpage and offpage optimization) + Paid Advertising (PPC, banners, text links, offline ads, etc.) = More targeted traffic and hopefully more conversions
Hi mrake, you can adopt various ways as suggested by other members here.
Like social bookmarking, SEO techniques , link building and many more.
But, I would like to add a bit here about security. Since you mention that it is an online shop, I hope that it has already an SSL certificate. They are just as important as a guard outside a safe. The data that your customers enters in their we browser is transferred to the server in an encrypted manner with the use of SSL security.
It is a means of establishing a secure connection.