For starters, you need to put the following into consideration:

1. Target Market – You need to find out the likely keyword or key phrase that your niche market is like to use to land on your webpage.
2. Domain Name – Use the keyword in point 1. Above to get a suitable domain name or website address that is both easy to remember and not misspell; and also contains in part or in full a keyword or key phrase that you are targeting. However, use not more than four words for a domain name. If a.com for example is not available you can try other extensions like.net,.biz or.org or even country code top level domains like.co.uk. among others which are mostly suitable for local search.
3. Meta Tags – Get a good title for your website, mostly use the main keyword first then a Separator followed by your secondary keyword. Secondly, get a suitable description for your site up to 250 words. The description should be sort of an elevator Speech that describes your website with minimal words including your keywords and key phrases. Lastly, on Meta tags: get suitable keywords and key phrases that your target web visitors are likely to use. Do not use irrelevant keywords to avoid unwanted traffic.
4. Alternate text – Suitable for use in images. It benefits the user when they are not able to see an image they can see an alternative text. Also Blind people can benefit from this. Search engines use this text to index you on image search. This creates more organic traffic flowing back to your site.
5. Style – Use headings and Sub headings to highlight topics and sub topics. The Headlines should include your primary keywords and Key phrases. Its recommended you use h1 tag for Primary Keywords and h2 tag for Secondary Keywords or key phrases.
6. Formatting – Bold and italicize various keywords and key phrases within the content of your page. Make it look natural and reader friendly.
7. Menu Bar – When you create a navigation links tab: make sure there is an empty tab at the beginning followed by the various links to your site. This allows search engine to index content on your page first and then the Menu links later.
8. Link to other Pages – When a page links to another within your site. It gives more value to the link page. For example if you make a five page site, and the fifth page is the “contact us” page, and you make every of the four pages to link to “contact page”. Search engines will view the “contact us” page as the most important of all pages and will be ranked high above other pages.
9. Keywords on Body – Use your Primary keywords at he beginning of the page at the headline preferably, mention the keyword naturally within the content body and also remember to mention it at the footer of page immediately after (c) and year.
10. New Content – Add new content to your site on an ongoing basis. Search Engines love fresh and unique content. So do your Visitors.

source- http://ezinearticles.com/?10-Ways-to-Do-On-Page-Search-Engine-Optimization&id=2971130