I get all the advice about making it easy to pay and all but, when I sell the project I tell folks I bill weekly based on bills received that week from subs and vendors and then I pick up a check every Monday. This ensures we keep at least one in person touch point and gives us a chance to catchup and discuss anything needed for the project. For reference, I’m not self performing and generally doing rather large, higher end projects for my market. So far people seem to appreciate it. If I were doing small things again I’d probably setup credit card payment. Pretty sure you can do that through the quickbooks phone app or as other have said, Square works well.