General Concepts
A Spider's quest to be human
Search engine spiders have two purposes: To find new web sites, and to score them for keyword relevancy. Finding the new web sites is easy. They find it by following links, and they index it. No problem. The difficult task is scoring. Every search engine's desire if to produce the most relevant results, so that when you enter keywords, the most accurate results for your search show at the top. The question s: How do they accomplish this?

Over the years, many search engines have developed extremely complex algorithms for their spiders to score with. On one hand they have tried to mimic what a human would react to, and the other hand they have played a cat and mouse game with search engine optimizers attempting to fool the spider into a higher rank. If nobody in the world ever thought to optimize their site for search engines, the spiders would have a much easier job. You see, the moment you optimize for a keyword, your site is no longer naturally ranked. So the spiders are designed to attempt to detect this.

All of this being true, spiders must score a web page carefully. For a particular keyword or key phrase, it has to detect if it is relevant, AND if it looks TOO relevant!

Over the years optimization practices have gone from very simple concepts to a highly complex game of balance. When search engines discover a tactic, they write counter-tactics into their spiders, and so on.

Remember this: Most spiders are designed to try to look at your site from a human perspective for information. Think about what makes a site good to you (aside from artistic value). You will tend to prefer sites with lots of information, lots of pages, and clearly written content. If you can do that with your site, you are ahead of the game.

Spiders have no appreciation of art.
Spiders are not human. You may have spent $10,000 on that amazing homepage graphic that everyone raves about, but all the spider sees is:

<img src="image.gif">

So no matter how attached you may be to that image, remember what the spider can see.

The same goes for Flash. Again, you may have won Flash Site of the year, but the spider merely sees the call to the flash, and ZERO content.

Weight, Balance and Substance
When a most spiders look at your page, they will look at the words on it, and judge how relevant they are by how many occurrences they find (including variations of the words), how close to the beginning of the page they are, and in which sections they find these words. Above all, they will look for substance. It there lots of info to digest? The balance of all of these will heavily impact your score.

Believe it or not, with the little information you have right now, you are more expert than most web masters out there. With this information and some common sense, you will be well on your way.