first you need to decide whether you want local traffic or global traffic... so that it makes your job simple. Need to spend lot of time on this and down the times it is also difficult to find the exact traffic.
Keyword Tracker will give you keyword idea and amount of total search data per month base on your seed keyword input.
keyword trackers provide local and global search traffic for specified keywords as well as competition for rankings witht ose keyword
With Keyword Tracker you can follow whether changes you've made to your site and the number of incoming links are having a positive or negative effect on your site's rank.
The keywords are the words people used much to express a product or thing, so you can visit youtube or forum to get some keywords. Then use google keywords tool.