Referrals from Personal Networks, Coworkers, and Other Participants - II

Unless you must keep it secret that the test is happening at all, we have found that putting the word out among our professional and personal networks will often turn up a source of participants or individuals who fit the user profile.
You may want to use people in your test who have taken part in other activities for the company. If this is not your first test, you may want to invite participants from the earlier tests back or contact them to get referrals to other people they know who might be suitable for your next test.
You might even have a form that your participants complete at the end of each test where you ask them if they'd be willing to participate in future tests. On the same form, you can ask for referrals (phone numbers and/or email addresses) of friends and others who might be willing to participate in a similar study.