Happy New Years GPT world!!!
This is a simple, but really helpful tip. Make a new email for every survey you complete. This sounds like alot, but Yahoo! Mail accounts take 30 seconds to make! Making a new email after every survey will almost guarantee a credit if you complete the survey the correct way. This is because many of the companies submitting the surveys to GPT sites use the same paths. Thus, participating on the same ads on the paths for multiple surveys with the same email, wont credit participation.
Ex. Pet Meds or whatever its called: Enter your name, last name, birthday and email. If you complete that for one survey then complete it for another with the same email, participation wont count for that second survey and you will most likely not get credit for the survey.
Make new emails very often, you'll be surprised at how much more surveys you will receive credit for!