Using Multiple Keyword Phrases For Your Site
First of all, if you are using multiple keyword phrases, you do know that they should each be specifically on topic for your web site right? Chances are though, a second longer tailed keyword phrase you might want to pursue is probably another topic of the main search term you began with. In other words, it is not the same as the original keyword phrase you are establishing. It has more of an emphasis on something else. Hope that all made sense so far!
Create multiple web sites! Design and optimize each web site for those "specific" keyword phrases. As a matter of fact, you could take the next step in SEO and go through another hosting service for your second web site.
Because those web sites will be on different IP addresses. If you use the same hosting service and create a subdomain, to the search engines (because they reflect the same IP addresses), they look at those two domain names as being the same. They "do not" look at domain names as you and I do. They are looking at the numbers associated with them.
"Everything on the internet has an IP address". This is how everything on the internet is recognized separately from each other. I was an internet engineer for over 23 years and can tell you this is how it works.
If you have a second web site from a different host provider, you will have a completely separate IP address. If you link those two sites together, it will do much for for your SEO than to have both reflect the same IP address.
Two things here: Keeping your topics for each web site specific to your keyword phrase and going to multiple hosting companies will make your site look like two separate entities which could feed off each other.
Heck, you want to make it more powerful, add (or try to purchase) other domain names with different IP addressing.
There is nothing better than using SEO to drive business opportunity leads to your web site as these are the highest of quality leads you can obtain. They are specifically looking for what you have to offer!