Just a thought on keyword selection: An effective way of checking how much competition there is for a certain keyword is to use Google's advanced operators. There are quite a few of these, but three of the best are "inurl", "inanchor" and "intitle".
If you just use these on keywords you're interested in optimizing a page for, you'll get some very valuable information. Basically, if there are heaps of results coming back when each operator is applied, then it might be very hard (or impossible) to compete for that keyword. But if there aren't so many, you should start ranking highly for them quite easily.
Of course it's hard to tell exactly what the threshold number is, but I found from experience of using one keyword on a site that even though there were tens of thousands of results for each operator search for it, I still ended up on page one in the SERPs. I think that the reason was that the keyword was in my url, the title and in my link building campaign (that is, frequently in the anchor text of the links I'd placed on other sites). These had a cumulative effect, I believe.
So, my advice is to choose some keywords that you really want to use, check that they have reasonable search volume, then apply these operators. Then just optimize for the ones with the lowest competition, making sure to have it in the URL, the title and in the anchor text of your backlinks to your page.