There are 3 main questions you should ask yourself when you first decide to perform SEO on your site and start the process.
1. Relevance: Is this phrase even relevant to your site and its content?
2. Search Frequency: Are people even searching for this phrase?
3. Competition: How competitive is this field? Is it even a feasible target?
Now, to get started…
Sit down with a pen and paper, and just start writing. Create a list of relevant keywords and keyword phrases. At this stage, there are no wrong answers. Write down all keywords that come to your mind, that describe your product. You can then move to your current website and any branding material to pull out keywords that already exist.
Second: Keyword Tool
Now, take that keyword list you generated in your brainstorming session, and insert it into your favorite keyword tool. Internally, we use Word Tracker. This tool will aid you in finding even more keywords based on your base list. It will also give you some semi-accurate information as to frequency of searches vs. competitors.
Third: Search Frequency
Once your keyword list has been given values in regards to Search Frequency, you can scroll through the results and pick out main keyword phrases and secondary keyword phrases. A keyword phrase with 100 searches a month may be perfect as a secondary keyword phrase, but in most cases may not be best as a primary keyword phrase.
Fourth: Compare Competition
After you determine a primary and secondary list based on search frequency, you should then compare the amount of competition that each keyword phrase has competing for it. The lower the number of competitors, the easier it will be to out maneuver them within the SERPs. You can determine your competition’s relevance, by their Page Rank, amount of backlinks and sites optimization for that keyword phrase.
Last, but not least: Choose 1 Main Phrase
It is usually best to focus on one main keyword phrase and build a strong foundation based on that keywords and a bunch of supporting keyword phrases. The amount of keyword phrases you can target is a direct reflection as to the size of your site. The larger your site, the more keyword phrases you can target and optimize for.
Once the Keyword Research phase is done, the fun stuff comes. Go optimize your site!