Generally, search engine optimisation consists of two main methods; on-page SEO and off-page SEO. Both are necessary to ensure you get good search engine placements for your web site.
On-page search engine optimisation techniques involve choosing the right keywords for your web site and including these in the text that appears on your web site. The way a web site is structured is also important so that a search engine can easily read and index the content and know which parts of the site are most important.
Things that can be done off the pages of a web site to improve search engine placement are referred to as off-page SEO techniques. It involves building links on other web sites that point to the web site being optimised.
Keyword Analysis
The first step in optimising a web site for search engines is to choose the right keywords. These need to be appropriate for your products or services.
A good keyword or phrase is one that is not only relevant, but there must also be enough people actually using that term in their searches for it to boost web traffic.
Certain business areas are highly competitive, and therefore getting good search engine positionings for generic terms can be competitive too. It is often best to identify niche keywords and phrases that better define the product or service being offered. For example a company offering a car valeting service in Southampton would find it hard to achieve a good search engine placement for the search term "car". In any case, most of the traffic generated from this search term would not be relevant; people would be looking for car sales, repairs and other car-related services, not necessarily valeting. A more sensible phrase to optimise for would be "car valeting southampton".
High Quality Original Content
When search engines determine a web site's relevance for a particular key phrase, one of the ranking factors they employ is to examine the keyword density; how often a particular search word or phrase appears on that page as a percentage of the total number of words. Getting the keyword density high enough ensures that the search engines see the page as relevant for that phrase. Too many occurrences of the term on the page, however, can lead to penalisation, causing a fall in search engine placement. Getting the balance right, therefore, is key to the success of SEO.
Web pages need some pages of content to enable them to contain keywords at the right density. It is best for this content to be original because some search engines penalise web sites that duplicate content from other sites.
Also important is reaching the right balance between search engine optimised text and readability; too often optimised pages are written almost entirely with the search engine in mind with little regard for the human that will be reading them.
Web sites that experience the most success from SEO tend to have new, original content added on a regular basis. This encourages search engines to come back regularly to index new updates and helps to give more importance to a site in a search engine's "eyes".
Web Site Structure
Correct structuring of a web page is essential to show search engines which parts of the content are most important. Proper use of hierarchical heading tags (h1, h2 etc.) and emboldened text is used to accomplish this.
The links between pages should be easy for search engines to follow and should consist of text links rather than image links where possible. Search engines can understand text, allowing them to get some idea of what a page is about just from the text links that point to that page. When hyperlinks are made up of images rather than text, search engines cannot read the image and therefore can't gather any information about the page's content from the link.
Link Building
The number of other web sites linking to yours is one of the main ways that search engines gauge the importance of your site. These sites need to be on a similar topic as your own and are best as one-way links rather than reciprocal.
The number of in-bound links to your web site needs to grow organically over time. Search engines look at the increase in links to your site over time and give the best rankings to sites that show steady growth, so this part of the search engine optimisation process needs to be on-going.
It is important to realise that search engine optimisation is a long term process and often takes up to six months before results can be seen. If a more immediate return on investment is required, then a Pay-Per-Click campaign can be employed until the optimisation starts yielding results.
White-hat / Black-hat SEO Techniques
Many people use dubious techniques such as cloaking (whereby a different version of a page is displayed to humans than is shown to search engines), or hidden text (where keyword rich text is hidden from human view by colouring it the same as the background colour). Such techniques can work in the short-term, but search engines are continually getting cleverer in order to spot such trickery. Web sites employing these methods are quickly penalised when found out sending their traffic plummeting.