What to do about keeping track of patron orders?

I've just taken over a small restaurant, that has no system what so ever for keeping track of customer orders - ie. Customer places an order with the waiter, waiter takes a slip to the kitchen, waiter rings up the order on a basic till, customer pays. How exactly would I keep track of which receipt in the till goes with which drinks/food order in the kitchen/bar/waiters book?
Thanks, any help will be really appreciated. Unfortunetly, this place cannot afford a computerised system at the moment, all thanks to staff theft and the sort.