Concentrate on your keywords: Place your keywords in title, Meta tags, header tags (H1), body text, alt tags, footer, and back link keywords.
Put a good sitemap: As sometime it is necessary to put our menus using javascript or flast or may be image, search engines can’t track our pages through the links. So we have to create a sitemap and put all the important links into it.
Content is king: Always update your site with fresh and unique content with proper targeted keyword density.
Website usability is queen: Make your website user interface design in such a way so that people can easily get quickly what they really need.
Quality back links: Continuously build quality back links where the anchor keywords and anchor titles show be your target keyword. Always concentrate on quality back links rather than quantity. Try to get back links from .edu ,.gov sites and high page rank sites..
Website link structure: Link structure must 1-2 level depth so that search engine spider can easily crawl you all pages. All pages must have unique title and content. Put your home page link in all your internal pages.
Do SEO while Design: Design your website using SEO strategy. Before design the website make sure that your designer should have the expertise of the rules organic SEO.
Canonicalization issues: Make sure www.yousite.com, yoursite.com, www.yoursite.com/index.html, yoursite.com/index.html should 301 redirect to www.yoursite.com or yoursite.com else search engine will think that all are different websites.
Static URL: Convert all your dynamic links to unique static links because keyword based URL is one of the best things to put your site in search engine results.
Flash, Frames and Ajax Problem: Keep in mind that the content in frames, flash and ajax are not crawled by search engine spider so if it is necessary to put those things in your pages then also create one static text based pages for your important keywords.
Optimize images: Put your images with maximum reduction of its size without reduce its quality. Put alt tag in your image tag. Always try to use captions below your images. Context placed near the image should speaks about the image.
Be Social: Keep update in Social sites like Facebook, Twitter, Digg, Delicious and other social networking and bookmarking sites.
Quality Videos: Build some quality videos and put them in major sites like youtube, yahoo video, msn video, metacafe, dailymotion along with descriptive text.
Be a good SEO student: Keep develop your knowledge in search engine algorithm. SEO is a ongoing process not a overnight deal.
Monitor Statistics: You should monitor your website statics to know that actually your effort of doing SEO is working or not.