Put all the keywords in Google Adwords keyword tool, I think you can put around 2500 keywords.. and check on the basis of global searches or CPC... Obviously higher searches keyword with higher CPC are the best one..
yeah that right, but try to group the keyword with tightly themed keywords. in this way, the similar trigger the relevant ads in the ad group.
Google keyword tool is the good one for keyword researching. i have used many time and got successful results. try that:.
I use market samurai or Long tail pro for that but I mostly prefer Long tail pro due to its simplicity and newbie friendly.