You can use Moz or Google Ad Words. For example, in Google Ad Words just try to come up with a few searches you may use as a search and Google will give you a few suggestions. Select each of these suggestions individually and you'll be provided the number of searches per month. This will be helpful to understand the most popular keywords to go after. As it's been mentioned before, try to go after the long-tailed keywords.

------------
Charles
Wholesale Rental Supplies
Wholesale Hotel Items