Keyword Research--Step One in SEO
Before you code a line or write a single word, you should start doing keyword research.
The first thing I want you to do is go to goodkeywords.com and download the tool they have there. It will tell you the number of times a keyword or keyword combination has been searched for over a period of time.
While it shows a "number," it's not quite accurate. Overture gets 8 to 10 times fewer searches than Google per month. But it's a good indicator of how popular certain search terms are.
Now--you're just starting out, and your chances of getting ranked highly for a generic keyword are slim. Instead of trying to optimize "keyword", try to optimize something a little more specific, like "Keyword Research".
You really shouldn't write for the engines. Write your content so it's fresh and readable, and design your site so that it's easy to navigate.
If you write about your keywords and use them in your content you'll be fine.
Remember, sites that are written for humans, with SEO in mind, will do better in the long run than sites that cheat.
Your ultimate goal when you research keywords (both for high-paying keywords and keywords that get a lot of traffic) is to find a happy medium between the amount of traffic you can expect if you rank well and the amount of competition you'll have. If you can't rank well for your chosen keyword, try to rank well for a related keyword combination.
Your keyword research should be a factor in your meta-tag writing and your page titles.