Keyword strategies: There are many names for strategies to utilize certain keywords in certain ways on a page to entice the search engine to rate it highly for those keywords.
Linking to and from other sites: There are one-way links, your site to another or theirs to yours. Then there are reciprocal links, where two sites agree and link to each other. The importance of some of these methods is debatable, but generally, relevant links to your site are of value. Relevance being a link from a travel site page about your area to your real estate site as an example.
It's a moving target. There are huge books and hundreds of thousands of web pages that study and promote various strategies for SEO. Just know that it changes regularly. For every new trick someone finds successful, there's usually a modification to the search engine's formula to negate it. The best overall practice for your web site will be to have a large amount of interesting and useful original content.
