Doing proper due-diligence will save you a lot of headache and aggravation in selecting a host agency. Research, reading and preparing structured questionnaire to use during your due diligence will provide you a quantitative reporting matrix and intelligent way how to choose a host agency. Selecting premiere name brands host agencies like American Express, Carlson, etc. is a sure bet that you'll be in good hands, but premier host agencies requires strict-entry qualification process. Then there are 2nd-tiered host agencies, which littered with pyramid scheme - not all of them are scammers, but without proper due diligence you will likely fall into one. There are independent consultants that you can hire for few hours to provide you an overview of the industry and the players before settling down on choosing a host agency. The following links will provide you a good starting source to conduct your due diligence:

Selecting a Host Agency Partner - By Melody Fee, OSSN Vice President

What You Should Know About - Home Based Trade

NACTA Host Agencies - Alphabetical Listing