There are many different methods of SEO, not one set rule or indeed one set of specific rules, however there are a few fundamentals that I will discuss in a later article.
Different industries that are in good positions in Google all have different rules for why the are ranking well. The exact same techniques used for say a PC Shop would need a different kind of SEO application than say a Camera store.
There are however, some SEO factors that are always required such as inbound link building, submission to major search engines and correct use of meta tags. Be sure to avoid over submitting your site as it may get rejected! Try and make sure your site is included in directories relating to your sites content and where possible add anchor text.
There are also underhand methods of SEO that do not have longevity and are mostly ignored or rejected by major search engines. These methods should always be avoided as they will eventually get your website banned for good.
Meta tags are another important factor in good SEO, be sure to make the title informative, not too long and have one instance of your desired key words. Write the description as a proper description of what is on the page, do not be tempted to spam as many key words into the description field as possible, this will work against you in the long run. There is some debate over use of the keywords META field, some don't think it is necessary, well I believe they are wrong, it is necessary. True, Google may not hold it in the same regard as say Yahoo but it is still crawled by the robots, Google may not hold them in the same regard as other search engines but they can be used. Make sure you add any words or terms that are important and are mentioned in your page in the keyword field. Try not to overuse the same terms!
Learning SEO is very difficult unless you have the desire to succeed, there are so many aspects and methods to learn. Start with the basics first and if you are unsure about something use Google, Bing or Yahoo! Good luck!