My preferred method, which works well, is to view a key "phrase" as multiples of keywords or other phrases.
For instance, if I optimise a page for the phrase "horse racing jobs usa" I will have it in the URL, <title>, <description>, <keywords> and <h1>, <h2> and text for that page.
the URL would be ...com/horse-racing-jobs-usa.html
The beauty if this approach is that I have optimised the page for the EXACT phrase "horse racing jobs usa" but I have also inadvertantly (on purpose) optimised the site for the additional [BROAD] search keywords below:
- horse
- racing
- jobs
- usa
- horse racing
- horse racing jobs
- racing jobs
- racing jobs usa
- jobs usa
... and possibly other random combinations.
When conducting the keyword research I always start by asking myself, "what would I search for?"
On a separate note, Google doesn't (apparently) use the <keywords> meta-tag but the others do, so it's well worth using it properly. What Google DOES use, is the <description> meta, often as the site description displayed in search results and it puts reasonable significance on the early placement of the keyword/phrase in that description.
So, in answer to your question, concentrate on LONG-TAIL phrases, not the general 1-2 word keywords.
The best option is something like;
<meta name="keywords" content="best blueberry ice cream,buy blueberry ice cream,blueberry ice cream,how to make blueberry ice cream,blueberry ice cream recipes"
That's how I roll...!!