Site URL and Title
It is bettter to keep the site URL short and avoid long domain names. Also, a descriptive URL giving the idea of the page contents is better search engine optimized. For example, http://www.funsurf.tk/p/how-to-make-a-site.html is better recognized by search engines than http://www.funsurf.tk/page.php?id=3
Make sure your title is contains your most important keywords and the length is between 10-60 characters. Also every page should have a unique title. Don't just give a single title to all your pages.
Meta ContentTry to include unique Meta descriptions to all your pages in about 70-160 characters. Here also, give importance to keywords and include your most important keywords in the Meta Description. Also Meta Keywords are good to include. Include the most used keywords and avoid excessive repetation. Avoid excessive use of tags as it might affect your SEO negatively.
Headings and ContentTry to use H2 headings for titles. Use H1 only for the most important title. For greater SEO, use only one H1 title per page.
Images say thousand words. But Google is not able to read the images. So include correct Alternative texts in images. Also don't use excessive images as it will slow down your page load time and this is certainly not good for SEO.
Add more relevant text to your pages and increase your keyword density to have better SEO. Also don't copy/paste from other blogs as it can have a negative impact.
Frames, Flash and AjaxAvoid using Frames and Flash content. Search engines don't understand them and cannot read their content. Full Flash sites are always a bad idea as they both increase page load times and decrease page ranks. Excessive use of Ajax also delays page load times. Try not to include it unless necessary.
XML SitemapA sitemap lists URLs that are available for crawling and can include additional information like last update, frequency of changes, and importance. This allows search engines to crawl the site more intelligently. It is always a good idea to submityour XML sitemap to Google™ Webmasters Tools and to Yahoo Site Explorer.
BacklinksBacklinks to your site matters a lot. The more number of backlinks, the more is the traffic to your site and the better is the page rank. Instead of participating in link exchange services, it is recommended to make your online presence in social networking sites and try to comment in the blogs you visit.
ConclusionWhatever you do to increase SEO, content is the king. Remember that no one will visit your site again if he didn't find anything related to his search in your site. I've found many great sites from google search and now regularly visit them. I too have found countless sites that I don't visit. I've also noticed misuse of SEO in some sites and never prefer to click a link leading to those sites as I'm pretty sure that the site doesn't contain any relevant content.
A blog always have greater page rank than sites due to its everchanging contents. So update your blog frequently. Do you have more tips? Please share with us.