For the longest time, keywords have ruled the SEO game. They aren't the only means to success in the Internet marketing business, but they are still the cornerstone of success. Learning to take advantage of keywords like a pro greatly improves your chances of your website ranking high and getting that much-coveted traffic.
SEO techniques abound, but the most important is what you do with your text content. Where and how you use keywords on your site's content can make or break the game for you.

• Work for keywords that have potential. By potential, I mean either earning or traffic potential, or both, whichever you want. Some niches and consequently, their niches, get a lot of traffic, but don't make much money. Other keywords get less traffic, but have better prices (that is, advertisers pay more for them). Beware of keywords that get little traffic AND have a low price set on them. You should avoid those. If you target keywords for money, look for words that have high advertiser competition. Use Google's AdWords Keyword Tool to research your niche.
• Use keyword families that are related to one another. Targeting an isolated keyword is impractical. People don't always use the same exact keyword to look up the same topic. A phrase such as "SEO keywords" may be searched as "keywords and SEO" or "keyword optimization" and countless other variations. Incorporate various renditions your keywords for better coverage.
• Write keywords in a natural style. When you use keywords excessively, you are making spam. Search engines hate spam, and so do readers. Do not overuse keywords. This doesn't mean you need to make an exact count of each word as it occurs. Just write content the way you talk about the topic-- naturally.
• Place keywords where they count. That is, in your titles, meta tags, headings, each paragraph of an article (the higher up, the better), and links to your other articles. Without proper labeling of your content, a search engine would have no way of knowing what it is about. So practice good keyword placement.
• Link to your keyword-targeted articles. You can link to your articles from within the same website. That is called internal linking. Many Internet marketers also engage in active link-building campaigns. You can write guest articles for other websites or blogs, and link back to your website. You can also link to your site in your profiles in forums, email signatures, social profiles and more.