Usertesting is the best website in its field. Considering the payout, the time it takes, and everything else, usertesting can easily help you make between 100$ to 400$ a month by just spending half hour a day on average (well, not everyday; only counting the days you get selected for tests). You just have to speak out loud honestly. Remember they are not testing you but their prototype/website/app or just asking question about your work or something. Just maintain a high rating of yourself and be honest; usertesting can be very rewarding.