If you're interested in optimizing your website for "Jacksonville Beach" a good place to start is with Google Trends. Here's the breakdown of the area beaches and how they stack up in the Google Rankings overtime. This is handy to know for prioritizing your content optimizations in any local SEO campaign.
Trend Comparisons for Jacksonville Beach related Google Searches
In everyday terms it simply means using the keyword phrase with greater number of seaches first. That seems obvious, but a lot of web developers and designers don't even know to reference any real data sources to guide them. An experienced SEO expert guru will not only look at Google Trends but also delve into several other data sources to cross reference other metrics too, like competion and retention information or demographic metrics to further fine tune the keyword selection.
For example, "Jacksonville beach" is obviously the larger audience but what if you want to filter out vacationers and tourist? Maybe your local business relies mostly on local residents within the Neptune Beach area (between Atlantic Beach and Jacksonville Beach). You might want to focus on the smaller but more relevant audience of Neptune Beach related keywords (your specific "geo modifier"). The keyword selection refinements go on almost endlessly from there once you have your "geo modifier" selected.