There are many ways of payment. some sites (like google) pay u through cheques. Some sites pay you through online banking sites. You get a unique id on this site based on which payments are made. The money in these accounts can be retained by requesting for a payment (transferring directly to a bank account using credit card or by cheque delivered home)

So keep a account ready before getting involved. Learn about this and get idea about these following sites by visiting them and reading their terms. For a basic account they don't charge you any thing so go ahead and create an account now.

some of the trusted sites are :

Paypal

Egold

MoneyBookers

StormPay

AlertPay