What not to do
While there are thing sthat will help move you up the list, there are certain activities taht may get you penalised or even banned from a serach engine as they are against the terms of use. so avoid these activities, called "unethical seo". Unethical SEOs can get your site banned from a search engine forever. Here are a few you really want to avoid:
Doorway/Gateway pages: This is a page which is solely for the purpose of being optimised for a serach engine and not really designe dfor human visitors - who will be redirected to another a page. Also known as cloaking or mirror pages.
Keyword StuffingThis is creatign a page that is crammed with your keywords, usually not as part of sensible text. Also known as Keyword Spamming.
Link Farms: These are sites that are just lots of links to try to fool search engines into thining that a site has a lot of relevancy. Don't do it - but do use link exchange with sites where crosss linking makes sense.
Hidden text and links: this is content not visible to human visitors and is frowned upon by the search engines.
Duplicate content: multiple pages and domains that say pretty much the same thing. This can get your ranking penalised.
Have a look at what the search engines say about quality:
Google webmaster guidelines
Yahoo content quality guidelines
MSN guidelines for successful indexing