Once you find a nice niche... in order to properly target an audience in that niche and maximize conversions, find out what they are a looking for. What types of questions are they asking? Then find the solutions to those questions and write about them.... How do you do that? Spend some time to find and list the forums and hangouts of these people and watch the boards. As soon as someone asks a question, answer it on your website, then also answer the question on the forum with a link to how you helped them. Hmmm relevant backlink that gets you traffic? Sounds like Penguin 2.0 love to me.
Some of these terms may not even register for search volume in Planner but it exists. And so what, you spent time writing an article to answer a question that over time made you 150 bucks... is that not worth it?
Targeting needs is far better than targeting broad traffic, as you will get a lot of bounces from people whose questions you are not answering. However properly targeted people will stay on your site longer, and share more and ultimately buy or click on your solution.
So keep in mind competition may not be as relevant as you think. By answering all these needs or issues for people asking specific questions, in time you will become an authority and start to rank for many many more KWs and sometimes, even the broad KW you were originally attempting to target. KW research is a huge part of a successful website. You need to treat each site you create as a mini business.... it could eventually turn into a big business.
There are lots of tools out there for judging this or that, but remember, big G isn't the only game in town. For example, did you know that yahoo properties had more traffic then any other company out there? Did you know that for many, email and social outweigh their organic search traffic? If you properly provide solutions to people's problems you will eventually build a nicely targeted following, just sayin... and in today's panda/penguin/hummingbird world, you have a better shot of ranking than you think. Just my 2 cents on your topic...