If you have a website, then just set up a page for payments. Arrange a Paypal account, drop the html code on the page and there is a button for the customers to click on. That takes them to the Paypal site and everything is done automatically, you receive a confirmation email that cusomer has paid.
If you don't have a website, but you get around your round on time, then set up Direct Debit payments, for the agreed amount each month.
We can't get round on time so are unable to go that way.
I do have some customers that want to pay by Bank Transfer and as long as they put there address on, that is ok as well, but have to keep your eye on the bank statements.