cash, check or charge... If you mean in what increments, its like anyone else you hire for a service. Usually a 1/3 or deposit upfront, then a 1/3 as you see the progress they are making that they promised and the last 1/3 when they are finished with the service they are providing. Be sure to get in black and white what is expected of them and how the monies are to be doled out. If you add anything to the original agreement then only the amount you pay out partially changes, unless something at the last minute has to be paid in full, then that money comes from you and you get the name and number of the person and get a receipt, paid in full... Good luck.