If my cashier badgered and nagged me like Sirloin suggests, the cashier would get hit. =^) I want them to print the ticket and send it back, announce the order --ONE-- time, then let us fill it. Don't need coaching and reminding, just the tickets. You decide what works for you.
Intelligent order taking makes a great deal of difference. We've found that in the customer's mind, the clock starts ticking when they place the order and you take their money--not when they get in line. Up to the time they order, they don't blame you if they have to wait because they are free to leave if the line to order is too long. But after you take the order they are captive.
So I lean hard on the cashier not to take more orders than we can turn out in 3-4 minutes. If the cashier takes orders as fast as the customers can say them, and 20 orders stack up, then those 20 people are going to be waiting a very long time before their food is ready and they are eventually going to get pissed off. Whereas if we don't take orders faster than we can deliver them, the customers perceive that everything is happening much quicker.
In reality you are producing the same amount of food in the same amount of time, but in the customer's perception the order was produced quickly because the time between placing the order and receiving it was short. It also makes for a far less stressful day for you and the staff.
I've never had customers who don't know how to queue up, can't help you with that. I would probably turn to orange cones. Here at Tamale Trolley we are big believers in orange cones.