If you are seeking to do business within your county, or even within your state, I'd advise you to get out to as many networking events as you can.
This accomplishes several goals. You can "mine" the members; telling them what you do and who you are seeking to connect with. You can also get instant feedback about your elevator pitch (which may need to be refined so that anyone you interface with "gets" what you do). Of course the importance of this is that in order for someone to make a recommendation to you, they need to fully understand the benefit(s) of the software you are seeking to sell.
If you planning to go national or even international - getting the kinks worked out via local/regional sales efforts is to your advantage. Once your ready to broaden your outreach, my first suggestion would be for you to connect with SHRMA - the main Human Resources support organization in the country ( since odds are that HR folks in all sizes of organizations certainly use temp staff agencies).
Best of luck with your efforts!
Ray Silverstein is the president of PRO: President's Resource Organization , a network of peer advisory boards for small business owners. He is author of two books: The Best Secrets of Great Small Businesses and the new Small Business Survival Guide: How to Survive (and Thrive) in Tough Times . He can be reached at 1-800-818-0150 or email@example.com .