I am working on the shopping portal, it is completly an e commerce shopping site. Having more than 4 lac products for sale. What is the best way to optimize the site? I am talking about the on- page optimization the url of the site is http://shopping.indiatimes.com
That is a very vague question. I just checked out your website. I would recommend you use more search engine friendly urls. It is rare that you see a url longer than 100 characters that ranks well. Try making a sitemap to submit to Google webmaster tools. That should help you resolve any crawling or indexing problems.
I think a first time you need to optimize your meta description, your meta title after you need to have a google Titile in H1 balise Sorry for my english
You should concentrate category names and relevancy of title for the each page. and try to build links for all categories pages with anchor text.
create normal site map & xml sitemap and submit to webmaster tool, you select best keywords and concentrate on SEM.