Does it cost money to sign up for GPT sites?
No, It doesn't. If the site is not offering free membership, don't signup.
How much will I earn?
There are many factors that influence your earning -->

your activity in the site.

your downline's activity.

your participation in Earning and Referral Contests.
How do I get paid?
Common payment methods are by check or PayPal. You'll have to request to get paid by clicking on "withdraw" or "cashout".
Why do they pay you?
Your info helps companies and advertisers to understand what customer think about their products or services. The money they pay you is nothing compared to the money they will gain from promoting their product or service and knowing customer's opinions.
Can I do an offer more than once at the same GPT site or at different gpt sites?
No, you can't. It's called fraud.
Do I need a credit card?
No, you don't. You can earn just by completing free offers and inviting friends and family to join under you but if you want to increase your earning then you definitely have to start doing the paid/trial offers.
How can I avoid using my credit card?
you can Get a prepaid gift cards from any store to do free trial offers or any offers that require a credit card. It cost from 3$ to 6$ and you can put cash as much as you want. Prepaid Gift Card can't be recharged so it eliminates the risk of being charged a fee by the advertisers. Once the card run out of money, you can buy another one. You don't have to worry about cancelling the trial, being cheated or overcharged since it's not a credit card.
Why I was not credited for an offer?
Can I provide false information to complete offers?
No, providing false information violates the rules of gpt sites and can result in a reverse of payment or getting account on Hold.
Can I have multiple accounts?
No, you can't. Having multiple accounts violates the rules of gpt sites and can result in a reverse of payment or getting account on Hold. Most of the Gpt sites tracks all ip address. If more than one account have the same ip address, those accounts will be marked as cheaters or placed on Hold.