This is where it's important to check out your competition so you take the keywords/keyword phrases that you've isolated and you open up Google as well as a page rank checker tool - Google's PageRank Checker is totally free to use.
Use quotes around your keyword/s and search in Google to see how many sites are competing with you for that keyword, now if I'm looking at a niche keyword phrase that attracts 500 monthly searches and there are 5 million sites competing then I'm going to look at the next keyword phrase that will work whereas if there's only 500,000 competing I may go to the next step.
How much competition you feel you can handle really depends on how much value you feel you can bring to the equation and how strong your competition is.......how do you determine how strong your competition is?
Enter the next stage - once you've found how much competition you have you need to analyze how good the competition is and how easy it will be to outrank them. I look at the top five sites on the front page and pop them into the page rank checker. If they are under PR5 then you can beat them with good content, if only one of them is a PR5 or higher than I would check the rest of the top ten and I'd still consider it a fair chance if the others were all really low.
If you find two or more with high page ranks then I would look at your other keyword phrases to see if you can find one that will still give you search results with less stiff competition.
Once you've found some great keyword phrases with low competition and you've written some compelling and unique information that makes people whip out their credit cards and buy buy buy then you'll want to treat yourself to a nice steak which means you'll need a lovely set of steak knives.
But wait theres more...........actually there's not, but I though you deserved some light relief after the boring nuts and bolts of keyword research!
I did promise to give you the steps I take in deciding which keywords to use, but that was before the big Google shake-up. I actually wrote the last couple of posts before I went on holiday so whether I'll have to tweak it further in light of the changes I don't know, but if I do you'll find out all about it.