Relevancy criteria
1) Administrative Features
The administrative features of a site are not especially important, but do have an influence on how well a site is ranked in terms of relevancy. This is particularly true of Google, which is the most popular search engine in the world. (Approx. 80% of all searches in the UK are performed using Google).
Domain Registration Features
a) One of the most important factors here is to have registered your domain as long ago as possible.
Longevity is counted as being useful for determining relevancy, so a domain that has been around a long time will generally perform better in the SERPs.
If your domain isn't fortunate enough to have been registered pre-2000, you can "future proof" it, by renewing its registration for 10 years, rather than the more standard 1 or 2. This is seen as an intention to be around a long time, and thus counts a little towards the longevity factor.
b) Changes of domain ownership can adversely affect your rankings. This is related to the longevity factor, in that the search engines like to see consistency of ownership, rather than multiple owners in a short space of time.
c) Country-specific domain extensions help for achieving a listing in a country-specific search engine (e.g. an .ac.uk domain helps for listings in google.co.uk).
d) Being an academic domain, Google will automatically give you a boost in the rankings for multiple searches, as it considers .ac.uk to be a signal of quality.
Hosting Features
a) Similar to the change of domain ownership above, search engines also like to see consistency of hosting provider.
b) Your site may suffer in the rankings if it is seen to be hosted on the same server IP as a site that has been "banned" from the index for dodgy SEO practices (see later section on Bad Practices).
c) Similar to the country-specific domain extension criteria above, hosting your site in the UK will help your rankings in the UK specific search engines.
2) Site Content
This is the area of SEO that has traditionally had most of the attention - primarily because it is the easiest to control, being directly related to how you develop the site and what you put into it.
There is, unfortunately, still a lot of nonsense around about the so-called "dark art" of SEO.
Certainly, it is impossible to predict what the major search engines will do next, and it is very difficult to "reverse engineer" the various algorithms - i.e. analyse the SERPs and draw up a set of rules and criteria for ranking purposes accordingly.
However, there are basic principles for the "on-page" site factors that are demonstrably key in achieving good results.
Some of these have been relevant since the days when the first real major search engine was king - AltaVista; whilst others have come to the fore over the last few years, or have had less / more emphasis put on them over the past 12 - 18 months.
We'll examine each of these factors in turn, starting with the most important, visible text content.