We've all done it: after ordering from Groupon to Go or your favorite pizza place, we haven't considered the proper food-delivery etiquette. And while there are plenty of articles out there on how much to tip your server, there is less out there for someone Googling "how much to tip pizza guy."

So we sat down with "Ray," a former delivery driver for a national pizza chain to ask him all our questions about food-delivery dos and don'ts, from how much to tip the delivery driver to what to wear when answering the door. Read on to learn more.

How much should you tip a delivery driver?

Short answer: On the issue of the pizza delivery tip, Ray says, "You can't go wrong with $5. That does the trick every time."
Long answer: If you wind up ordering 12 pizzas or enough Chinese food to feed a small army, make sure to tip beyond that $5 and give 15% to 20% of the total bill. Plus, a bigger tip may get you quicker service.
What's in it for you? If you do happen to tip well, that could equal better service in the future. "Word gets around fast amongst the delivery boys when there's a known hot tipper," Ray says. "They certainly get priority on our runs."
Why at least 15%? Though it may seem like driving around and handing people food is easier than the work demanded of a traditional server, it isn't. Delivery drivers are subject to a bunch of extra expenses, Ray said. "We have to foot the bill for everything: gas, [car] insurance, repairs ... [that's why] you never see a delivery driver in a Benz."

But what is a "delivery fee"?

We've all seen that $3 to $5 "delivery fee" tacked onto our bill, but Ray explained that the drivers don't see a dime of that charge, so customers shouldn't factor this surcharge into their final tip amount.

"It's kind of a sore spot for us, because customers assume we're already rolling in with a preset tip," he said.

What if my food arrives cold?

If your pad thai is too frosty to eat, don't take it out on your food-delivery driver. "It's usually the manager's fault," Ray said. That's because the manager is in charge of dispatching drivers and plotting their routes for maximum efficiency. This often results in a single driver receiving too many orders. But, Ray said "a gentle, non-yelling complaint" to your driver usually results in a discount on your next order.

You can also shave some time off by meeting the driver outside, especially if you live on a block where parking is hard to find. As Ray put it, "When I'm driving in circles for 15 minutes trying to find a spot, your pizza (and others') is getting cold."

What should I wear to answer the door?

Nobody wants to change out of their comfy sweatpants to grab their pepperoni pizza. It's one of the reasons we order delivery in the first place. Thankfully, pajamas or sweats are the norm, Ray said. He did have one caveat:

Can I place an order right before the restaurant closes?

It's one of delivery drivers' biggest pet peeves. If the place closes at midnight, and you're calling at 11:30 p.m., you're golden. But don't try sneaking in an order at 11:59 p.m. That's just poor form.

"We wanna go home. We've already started packing the food away. If you were in our place, you'd feel the same. We'll still take the order, but we're not gonna like it," Ray said.

Is it rude to order delivery when the weather is terrible?

You look out the window and see a blizzard or a torrential downpour. There's no way you're going out in that mess, so why should you force the delivery guy to? The answer is simple:

But trudging through the snow or getting drenched stinks, so tip a little extra to show your appreciation. The same applies to any situation that presents the driver with an unusual challenge, be it walking up eight flights of stairs or driving out to a dangerous neighborhood at night. If you're expecting the delivery driver to do something you wouldn't want to do yourself, give them some extra green if you can afford it.

One last thing...

If readers learn one thing from this interview, Ray—and delivery drivers everywhere—want it to be this: "We're hustling. Hard. And so many things can go wrong on our way to your place."

Like most jobs, food delivery is subject to factors that are out of the driver's control. Traffic, icy roads, construction, and customers who aren't home to answer the door are just a few of the obstacles a driver might face over the course of a shift. So be patient, be courteous, and, for crying out loud, be a good tipper.