Forget about commercial intent - it is completely BS and not to be trusted. It's a gimmick. I've written a full post here on my free keyword research method (or
http://drivingonlinesale...eyword-research-method/ since my links are not live at the mometn) that makes me money and helps you to optimize your results quickly (to make a profit). I give the complete method there and I give far more detail and it's written properly.
BTW - ppcBully, Google Cash Detective, Keycompete etc are BS, forget them and don't waste your time or money. The only one I would bother. However Keywordspy - even the free version has a lot of value. If I had to have any keyword tool that was paid I would use keywordspy. But in saying that with my method you are going to find 98% of those keywords over a 2 week period of testing anyway, so it's kind of not necessary really.
Anyway back to my method. Lets say you are interested in selling dog training products.So you root keyword is 'dog training'. The first thing you want to do is make a list of root keywords that are related to dog training. For example:
dog training
dog obedience
dog potty training
Then wrte separate themed modifier lists. Here is one list based on training solutions:
online
classes
schools
book
course
Now you can come up with tons of these grouped modifier lists, the key is to make sure they have some kind of monetizing intent. Don't use a tool, just use your head. I use google search, wordracker, and free keyword tool to come up with ideas for modifier keywords.
Then you download a keyword multiplying tool like the revenue wire keyword tool.
Then what you do is multiply your root keyword list with one of your modifier themed lists. Now I am aiming for keywords that are 3 word phrases. If the keyword is ultra targeted and obviously going to convert then sometimes I will go for 2 word long phrases, it's a judgment call.
Read my detailed blog post free keyword research method for the rest of the details, in order to compile a list of thousands of targeted and most likely money making keywords.