Jps, its very easy.
1. You go to paypal.com and set up an account for your business.
2. After it is setup, you tell your customers that they can pay thru paypal, they just need to set up an account for free. To pay thru paypal is at no cost, to receive thru paypal it is fee based, 3%, but don't quote me on that number.
3. Depending on the type of account you have, you can transfer funds electronically or request a paper check.
This method works really good for the customers that I have that use AMEX, they pay their bill and get reward points.
