1) Offer free, original, and quality content on your site
2) Optimize high traffic keywords related to your business , if your website will be listed in Google page 1-2, then you will gain high traffic easily.
3) Advertise your website in Google or other high traffic webs.
4) Get more external links
5) Improve general search engine optimization
6) Increase page rank, Higher Page Rank = Higher Search Engine Positioning = More Site Traffic
7) offer resource page links
8) Update your web more frequently which your audience love to get feeded.
9) Exchanging advertising or links.
Most important, be patient, if you use some techniques to increase traffic, more or less, the numbers go up but useless to your sales. Only those traffic related to your products could improve your sales.