It is generally a good idea to keep a close eye on your website analytics in order to know what search engine keywords are bringing visitors to your site. If you are already ranking for a particular keyword in many cases it only takes a few new links having the anchor text of that keyword pointing to your ranking page to boost your ranking a few spots. Considering the fact that click through rate increases pretty significantly the higher up you are in the SERPs, your time and money is often times better spent focusing on boosting rankings for keywords which you are already listed for rather than keywords which you hope to rank for but have not yet obtained a listing. You may end up spending a lot of time and money trying to rank for keywords which are ultimately out of your reach when you could have spent that same effort boosting rankings for keywords for which you already have a listing. You could reasonably expect to increase traffic from a given keyword ten fold by increasing your position from a 9 or 10 to number one , and at least double traffic from a keyword by moving from a 2 or 3 position to number one.
A few weeks ago I noticed I was getting a visitor from a fairly competitive keyword about every other day. When I checked to see where I was ranking for that keyword I found out I was at position 39 at the time. I figured it wouldn’t be too hard to boost my ranking to hopefully the top ten where I knew I would get considerably more traffic from that keyword, so over the next few weeks I kept that in my mind. Within a few days I was able to increase my position to the mid twenty range and was starting to get traffic for that keyword every day. My position fluctuated in the 15-30 range for about two weeks, but yesterday I discovered that I am now ranked #10 for that keyword, and I getting quite a bit of traffic for that keyword. This keyword seems pretty competitive so I think my time would be better spent going after some less competitive keywords going forward, but this experience solidified in my mind the value of keeping an eye on your analytics and spending the effort it takes trying to boost rankings for keywords for which you are already listed.