Web Site Sign-Up

If you are planning to do extensive testing, you will probably want to develop a database of qualified candidates for your product so that you can move quickly when it is time for a test.
Setting up a web form and a database to gather and store information about potential participants may take some nontrivial setup time, but once it is set up, you can sit back and watch the panel of possible participants grow.
Many large companies include links on their web sites that invite people to "opt-in" to their participant databases. The forms collect basic demographic and behavioral data generally related to the company's product line in the online form. By doing this sort of thing, when a study comes up, you can do a simple search of your database for key characteristics to narrow the list of likely candidates, whom you can then screen more specifically for the test you're about to do.
There are several advantages to this approach. One is that the people who sign up at your web site are definitely motivated to take part in improving the products they use. They probably have some idea about what you might be doing, that is, they are probably familiar with marketing focus groups, at least.
Because they have joined your list of their own free will, you are free to contact them about taking part in your research. One caution is that your sample may be skewed toward people who are particular fans of your company, or who habitually sign up for surveys, focus groups, and other types of paid research.
Update the database after each test, showing the date of the last test. The advantage of this approach is that you are always ready with a list of potential participants who represent the market breakdown for your product on short notice.
NOTE
Itl'lM Please note that depending on your needs and how frequently you conduct tests, it may require a full-time administrator to manage the database and manage the participant contact prior to the test