Search engine optimization effort can be categorized into three basic elements "Code, Content and Linking (CCL)" these three diverse elements play very important role in search engine rankings, you will come to know about their effectiveness and usability with some of the very useful tips in this article.

Code
Writing Code
Validating Code
Cleaning & Optimization Code
Cross Brower Independence
Robots.txt and Sitemap

Content
Content Writing
Formatting
Content Placement
Content Distribution
Content Updating

Linking
Internal linking
Incoming or Inbound linking
Anchor linking
Navigation
Site Structuring

Code
Code of the website is the very first element that is unfortunately ignored by most SEOs, website code allows search engines bots to go through the webpage, and if bots will not be able to understand code they will not be able to access content of the webpage because content is kept within code, this is enough to tell you about the importance of website code.

Code of the website has to be clean and optimized, here i means that code like JavaScripts or CSS should be called externally, try to keep your code as short as possible and ignore too much nesting.

You must validated complete website code either everything is working fine or not, check for browser compatibility, orphan pages and broken links, don't forget to have robots.txt and sitemap.

Content
Content is still king, no one can deny the fact that since the revolution of search engine in mid 90s, content is undefeated king. Content needs special treatment, today search engines automatically take keywords within content, they become more conscious about content, they follow basic fundamentals of writing techniques, such as headings, sub-headings, bullets & numbered, inverted commas.

Now it's up to you either you are successfully able to give an impression of your important keywords to search engines, try to use your important keywords in headings, sub-headings and try to start paragraphs with important keywords.

Note: - Here content means selectable content, content on images can't be selected and read by search engine bots.

Linking
Linking is one of the most important criteria to get better rankings in search engines specially in google. Linking is divided into two categories onsite linking and offsite linking. Onsite linking belongs to links that are mentioned at your web-domain either they are internal or external it doesn't matter, they have to be declare at your website (domain). Offsite linking belongs to links that point your web-domain from a different web-domain, they are inbound or incoming links to your website (domain).

In internal linking you should try to keep web pages as close as possible to root, if you have a big site of over 100 pages or 500 pages then you have to make relevant directories and keep relevant pages in them.

In link-building you have to keep few things in mind that link has to be one way, and link title and description should be very focus, try to have incoming links from relevant sites, since one relevant link is equal to 100 irrelevant links, when submitting to directories, go as deep as possible and try to find most relevant category where you can submit your site.