The truth is there are about 125 (or more) factors which ultimately affect your rankings. And Google has weighted them each differently, and won't tell us what these factors or, nor the weights assigned to them.
However we can make some pretty good guesses.
I've been optimizing websites for almost 6 years so I can speak with some authority. There are a variety of on page and off page factors. On page factors include meta tags, title tag, Header (ie <H1>) tags, alt tags, and page text. These all can impact google rankings, however slight.
In other words, the presence or absence of an alt tag or 2 won't dramatically (if at all) affect your final rankings.
That being said, what I've found is that it is the off page (or off site) factors which have the most effect on your rankings.
These are generally the links which point to your site. However there are many factors to consider here as well. They include:
The link itself - where does it link to? Your home page? your tld (top level domain)? Does it link to your
www.site.com or just site.com?
What is the anchor text on the link. In other words is it just "click here" or "link" or is it something useful and meaningful. Ideally the anchor text on your links should be your most important keywords.
What other words are around your link?
Is the page the link is on merely a page full of links, or is there other text?
If there are other links, how many? And are they related to your own?
Plus there's lots of other factors affecting your rankings.
So how do you help improve your rankings?
Well, if you feel your site is already well optimized, may I suggest a thorough
link building campaign?
Whether you hire a firm to build links for you, or you do it yourself is up to you. In any case you need to ensure that the links you build are:
a) from sites related to your own - these could be industry related, geography related or other relationships. Ideally a good mix of regional and industry links is recommended.
b) are the sites considered "trusted" or "authority" in Google? In other words, what is their PageRank? Simply download and install the Google Toolbar for your web browser and enable advanced features to see the site's pagerank. Keep in mind that the PR value shown in the toolbar is a little old, however it is a good indicator.
Once you know the types of links you want, you can start looking at your competitors links (for example) to see who links to them. Google won't show you all the links, so I'd recommend using a combination of Google, Yahoo and MSN to get a more accurate representation of the links pointing to competitors.
Once you have this list (and it will be huge) you need to start going through them and qualifying them based on the above criteria (relevant/related, and authority/high PR).
From here, see if you too can get a link.
Simple huh
