I will step through the steps I take to find the winners by starting off with a generic product niche "table". For this set of steps you will need access to 'Micro Niche Finder'

http://www.micronichefinder.com/

Step 1
Using Micro Niche Finder I run a query with "Table" as the keyword. I then use the check filtered results function and delete all keywords with more then 30,000 searches and less then 600 searches/month. I then go through and get rid of anything that doesn't have a semantic relationship with the main keyword phrase.

Step 2
I check the remaining results then run the 'Get Checked S.O.C' function. When this is complete I delete anything that has a S.O.C > 50 (i.e. non green). I end up with

"
kitchen table sets
pub table sets
glass top dining tables
glass dining tables
contemporary dining table
square dining tables
dinning room tables
contemporary dining tables
living room table
dinning room table
dining round table
dining tables round
"

Of course your results can vary based on google datacenters and etc. But for the most part you will get what I have shown here.

This is how I look for micro niche using Micro Niche Finder. However if you are short on budget, you could try using Google Keyword Tool. The only problem is you will have difficulty getting the SOC,(Strength of competition).

MNF is a great tool, if you want to succeed in the IM world, this is the kind of software that you should invest in.