Q: How do I know which keywords to target for SEO/onsite optimization?
A: Onsite optimization is an essential part of any business' SEO strategy, and it all starts with researching and selecting the right keywords to target. First and foremost, you should always make sure that each web page on your site targets a unique keyword (one word) or unique keyphrase (a series of words). No two pages on your website should ever target the same keyword, as you're then competing against yourself for the opportunity to rank in Search Engine Results Pages (SERPs) for that particular keyword.
Secondly, you'll want to ensure that the keyword you're targeting is the most relevant word or phrase to describe that page's central theme. So, for example, if you have a page on your site that focuses on the benefits of drinking green tea, the keyphrase could potentially be, "the health benefits of green tea" or "green tea benefits." When the keyphrase captures the purpose behind the page, to educate users about the benefits of drinking green tea, it's much more likely to drive qualified traffic to your webpage. As a business, you don't just want to just send more people to your site. You want to send more people to your site who might actually buy what you're selling.
Thirdly, it's important that the keyword you choose has "search volume" behind it. Search volume refers to the estimated number of people who search for a particular keyword. There are several free online tools available to obtain this data, such as Google AdWords' Keyword Tool. This tool allows you to enter in keywords to determine how many people search for those words either locally (within the U.S. only) or globally (internationally) each month. It also provides suggestions for keywords that are thematically relevant to the keywords you initially entered. It's a great way to not only better understand what users are actually searching for online, but to also seek out new opportunities for keywords to target that you might not have previously considered.
Finally, estimated competition should also play a factor in the keywords you choose to target. A keyword's "competitiveness" indicates how many other web pages out there are also targeting that same keyword. The higher the estimated competition, the more difficult it will be for your webpage to potentially rank for that same keyword in SERPs. Google AdWords' Keyword Tool can also be used to help you access the competitive landscape for any given keyword.