The casino payment methods sometimes slightly differ by casino, however, there are a few payment options acceptable by every honest online casino:

 Neteller - Since the credit card companies restricted the use of credit cards on online gambling venues, Neteller has emerged as the biggest and best third-party online gambling payment processor. Every casino which accepts Neteller as a payment option offers 15%-25% extra bonus when using Neteller for chips purchasing.
You can deposit funds in your Neteller account using your bank account and/or credit card, and there are several withdraw methods including overnight check, wire and more.

 Citadel - Offers a secure way of transferring funds fro your bank account to your online casino account. The Citadel Commerce group of companies emerged from years of providing consulting services and real time transaction auditing products to the highly regulated government lottery and pari mutuel gaming industries.

 FirePay - FirePay is a Web-based cash account that can be used by anyone who has a U.S bank account. A FirePay Personal Account is similar to a credit card. When you sign up for your FirePay Personal Account you will be given a 16-digit account number and an expiry date. Fund your FirePay Personal Account directly from your U.S. bank account, and immediately use the funds at the casino.

 Bank Draft & Wire Transfer - Depositing using these methods will earn you extra bonus on top of your deposit, however it takes a little longer for the deposit to show on your casino account.