First let me start by saying we own the building we train in so if we have one student or ten, it's not such a big deal to us. As long as we can cover the utilities, garbage, etc. we're cool. Over the 35 years we've been in business, we've had to put money from our pockets to cover things, sure, but those were pretty few and far between.
We like to have students pay around the same time every month {usually when they started}. This way we have money coming in all month long, not just the first of the month. You have bills coming in all month long, why not be sure you'll have cash coming in all month long too?
Over the years, we've had a few students who managed to wiggle out of paying much {or anything at all} but we can honestly say there haven't been that many. It is a slap in the face when students cannot be bothered to pay you for teaching them {or pay on time} and should be considered as such. If you're not worth their efforts to pay you, your teaching must be worthless too. This is a good practice to use on those folks who manage to be late all the time {or not pay at all}. Look them in the eye and ask them if they think what you've been teaching for 35 years is worthless? When thay answer you; "no", you can say; "well that's how we feel when you are constantly late, or don't pay at all." This usually works real well. I save it for the real bad ones.
Our school is like a family to us, and if they are having financial problems {or any other problems} we'd just rather they come down and train, never mind about the money. If we had to worry over the money, we'd have closed down a long, long time ago. So if someone doesn't pay, well, it's not the end of the world {be sure you do get the money for uniforms, sparring gear, t-shirts, etc. this is money you had to put out and it has to come back or you will go broke, fast!} But as long as the lights are on and the water is running, we're happy too.
This may not help much, but at least we all know we're kindered spirits.