This is an essay length question, but I presume you are selling products online? i.e. E-Commerce? We could obviously discuss link building till the end of time, so I will stick to on-site; get your house in order first and all that.

Pagination: Try and ensure pagination is kept to a minimum - a starting point is to ensure, as far as possible, that no page on your website falls more than five clicks away from your homepage. Remember, search engines utilise web crawlers to pick up and index content - you want to make it as easy as possible for the crawler to find all of the URLs on your website; your website is in essence centered around your homepage, simply because it's the most linked to page and the page crawlers are likely to visit most frequently. Five clicks is a baseline, the closer to the homepage the better.

Products per page: A solution to pagination issues is to increase the number of products displayed per page, it will also aid crawlability.

Product pages: Avoid, where possible, manufacturers product descriptions - try and generate unique content wherever possible. Ideally, try and get users to contribute content in the form of product reviews etc.

Top category pages: Ideally, try and get content in there - avoid interrupting the flow or the design of the site by using a CSS dropdown box i.e. click to read more/hide. See dabs.com and their homepage for practical implementation of this, scroll to the bottom of the page.

Filtering: Filtering options i.e. sort by price, sort by name etc can be an absolute pain in the ass for crawlers, mainly because it can, in some instances, results in the content being re-ordered (not changed) and a new URL being generated. Basically, it means another URL for the crawler to index without adding any value. Be very careful with this - even subtle things like a change in currency can create craw issues.

Basic canonicalisation (BRITISH spelling! )/duplicate content: Ensure, ideally, all pages resolve on either WWW or non-WWW, utilise a 301 redirect using a .htaccess file to create the desired effect. Other issues to look out for include trailing slash URLs and secure pages (below) - there are tons of these. The reason this can be a problem? Simply because the search engine can find the same page of content on two separate URLs i.e. WWW and non-WWW (if they both resolve). Which basically means the pages will be competing against each other for position in the SERPs (search).

Basically, just ensure that for every page of content you have on your site, it only resolves on a SINGLE URL, and no other.

Secure pages (HTTPs): needless to say, you don't want these to redirect - use a canonical tag; search for it for more info.

BASE FEED: Do this, very important - search for information about optimisation, would take me an age to write everything out.

This could literally go on forever, however hopefully that will start you off - above all else, watch your URLs; e-commerce content management systems are notoriously dreadful for the above issues. Have a look at Magento if you are still deciding.

SEO needs a lot of work, content, onpage optimization and backlinks (off page optimization). If you need help, pm me

Focus on your on-page and off-page SEO. On-page includes having comprehensive and informative content that are valuable to the readers and user friendly site – easy to navigate and fast loadable. Good content offers demand and leads your website to be linkable and will attract more visitors. It’s also important to optimize your site. Build quality links from different high authority domains - submission on article directories, creating contextual backlinks to web 2.0 properties, guest posting, wiki sites, social bookmarking and document sharing sites, creating blog posts, press release and video marketing.

nothing blackhat, you want to focus on gaining links from reputable review sites, try guest blogging, press releases and social interactions.

Advertising with twitter could help as well as facebook ads

Good luck its a competitive area