Search engine optimization is a much-debated topic and there is a lot of different on the net. Let's cut through the muck and discuss things you should and shouldn't pursue to get high rankings.
Before blasting into the subject, we need to define optimization. It simply refers to the manipulation of a site to gain top rankings on the three search engines that dominate the search traffic on the net - Yahoo, Google and MSN. If you do a search on Google, the optimized listings are found in the large section on the left hand side of the page. These are often referred to as organic rankings since you don't pay for placement. Of course, you manipulated the page for optimization, but we will stick with organic as a name.
The first optimization tip is the most basic and the one many people screw up. Pick the correct keywords for your site! The correct keywords are not what you personally think based on your knowledge of your service or product. They are not the phrases returned in the Overture inventory tool. The only place you will find the exact keyword phrases you should use are in Wordtracker. The site gives you an analytical tool that provides the exact keyword phrases being used by your prospects, how often they are being used and which are easiest to get high rankings on. It costs a whopping $8 for a single session, but you will want to get a year subscription so you can pick up different cycles of keywords. Your prospects will search for different things in summer compared to winter.
The second thing to consider is the isolation keyword strategy. Many people will try to cram as many keywords into a page as possible. The accepted standard is 10 to 15 words. This is an old approach that works, but it will take much longer to get high rankings. Instead, you should develop a list of as many keyword phrases as possible. A single page should be made for each keyword phrase. You should never have to pick one keyword phrase instead of another for your site. Instead, you should make individual pages for each phrase.
A major third optimization tip is interlinking. The links from one page of your site to another matter a lot. When you create a link, make sure the link is the anchor text for the page the prospect will be going to. Anchor text is simply the keyword phrase on that page.
Turning to things you should avoid in optimization, well, there are a lot. Do not put your site name in your meta title, the search engines will list you high without it. Do not skimp on text, you need at least 250 words per page. Do not put database parameters in your urls because spiders have problems reading them. Stay away from flash as much as possible for the same reason. Stick to a single subject per page, to wit, do not wonder around like a drunken web designer! For the love of God, do not use frames. Finally, keep your html code streamlined so search engines can read it with ease.
The list of things to do and avoid is nearly endless. Follow these simple steps, however, and you will see marked improvement in your rankings.