On Page Factors

All search engines reads the web pages.so first write a lengthy and sense able content on your web page.you have to take care about keyword density also.if you are writing againest high competitive phrase (or keyword), your page's keyword density must be low. on the other hand keyword density must be high againest low competitive phrase.
Use sense able alt tags for all the images, so search engines can make a sense for your web page's images.it will be help you in image optimization also.
Comment tags are helpful to understand page's scripts (or other coding part),but it is not useful for search engines.your title and description tags are much impotent.place your competitive keywords into that tags as left align.

Thanks
susheel Singh