Pillars of SEO !

1. To have short URLs with productnames, categorynames and having keywords in these links.
2. Canonical URL links in the HTML header.
This is for the search engines to look at this tag and to digest the page in question should be treated as though it were a copy of the URL and that all of the link & content metrics the engines apply should technically flow back to that URL.
e.g.

<link rel="canonical" href="http://hostname/product/en/abc350" />
<link rel="canonical" href="http://hostname/category/en/s_furniturechair" />

3. Generating Google site map periodically.
4. XML site map and keeping at the root of the shop.
5. Link building and using Fat Navigation\Fat Footer With using key words in links.