A number of factors need to be considered when optimising a web site for the organic results of the search engines. The cumulative effect of optimising all parts of a website is greater than the sum of its parts optimised individually.

Each factor overlaps with, or is related to, at least one other, and for maximum results the big picture needs to be captured by a search engine optimisation strategy.

This article outlines the elements an effective SEO strategy should cover.

Content

Body content should be relevant and not copied from anywhere else. The density of keywords and phrases should be approximately 5%. Related keywords and phrases can be used to boost relevancy.

Search engines like to see that a web site is serving current and valuable information. Frequently changing content and the addition of new pages will keep both search engines and users interested and can improve rankings.

Titles tags

Titles are the most important tag used by the search engines for determining the topic of a page. They should be relevant, concise, not use repetition and unique to every page. A call to action can encourage click through from the search engine results pages

Inbound links & PageRank

Due to the democratic nature of the major search engines, a web sites reputation is based on the number of relevant and trusted incoming links. The better the reputation, the higher a web site will usually rank. Reciprocal links carry little weight these days. Editorial citations have the most value as these are nearly always human edited.

Indexation

Generally speaking, the more pages a site has indexed, the better its chances are of ranking high. Certain infrastructure and content issues can hamper or even prevent the indexing of pages, and thus, have a negative impact on rankings.

HTML/XHTML & CSS

Weight of keywords, relevancy of a page and a site as a whole and its 'crawler-bility' (the ease at which a search engine can read a sites content) can be maximised by effective use of CSS, HTML and XHTML.

Meta tags

Whilst meta tags are no longer used by the major search engines for ranking, they must still be unique to every page and have certain limits placed on character length.

For the purpose of ranking, meta tags can actually be omitted altogether. However the description may be used as the snippet in the search engine results pages, so there is an opportunity to increase click through rate.

Keyword choices

The choice of keywords is essential to determining the relevancy of a page. Targeted keywords should be placed in the title tags and sprinkled evenly throughout the body copy, without making the text contrived or the keyword density too high.

Internal link structure

The internal linking structure is paramount to how a site is ranked. Search engines like to see a clear and logical hierarchical structure. This improves crawlability and can help maximise internal PageRank, which solidifies a web sites ranking position. Search engines also give more weight to links found within body content as these are usually human edited.

Spam

Any activity that falls outside the search engine guidelines is considered spam. The potential penalties range from negative impact on rankings to permanent de-listing.