Every client will be on a full service maintenance contract or if they just want to do fert/weed control, those services are billed the day they're done unless prepaid. I HATED having people try to cheap out and want to skip mowing for a week. With a monthly price, the money is always received and the client is almost always happy. Win, win.
If its an install, 50% up front received and then we begin and then the remaining 50% upon completion.
The only thing that would be per visit is plowing.