Working for gig economy services is easy, but making it lucrative is a bit harder. You depend on the tips from the customers as a good chunk of your income. But what do you do if customers don’t tip you, or never seem to tip you enough?

Here are a few tricks to consider.

1. Be Friendly

This should go without saying, but if you’re rude, you’re not going to get a tip. While not everyone is a smiley, bubbly person (and that’s fine), basic politeness has been shown to increase tips.

Take a page out of the food industry’s handbook (yes, they did academic research on this). Try to introduce yourself by name, ask them how their day was, and try to joke around—anything to appear friendly and approachable.

A smile might be the most important. Smiling has been shown in some studies to increase tips by 140 percent for food servers. With on-demand delivery providing growing competition to the food service industry, there’s no reason we shouldn’t pay attention to what’s worked for them.

2. Dress Properly

There’s no reason to wear a suit and tie as a courier, but you should look professional. Many couriers have reported, for example, that tips go up when they wear a collared shirt versus a t-shirt and shorts.

The issue of dress really comes down to how you want people to perceive you. Are you “just the delivery guy,” or are you a professional providing a professional service? Do you want to be tipped as the delivery guy or the professional?

3. Be Thorough

Check your customer’s order before leaving the store or restaurant. Even though it won’t be your fault if the restaurant puts the wrong thing in your delivery bag, the customer is likely to put your face to the mistake—because it’s the only face they’ll see.

Make sure to plan for the things that will be your fault if they go wrong—like melted ice cream or cold pizza. Make sure you have adequate coolers and carrier bags to keep food just as hot, cold, crunchy, or soft as it was when it came from the restaurant kitchen.

On a related note, if an item is unavailable and the customer hasn’t given specific instructions, take the moment to call or text the customer. Don’t just guess. Communication shows you care and helps leave your customer satisfied with the experience.

Likewise, if you’re going to be late in your delivery for some reason (traffic seems a likely culprit), call or text your customer to let them know. They’re much less likely to be upset (and take it out on your tip) if you communicate ahead of time.

4. Give Them the Receipt

This is our personal favorite trick here at Courier Hacker. You can read a more detailed explanation here, but basically, if you want more tips, give your customer their receipt.

If you just ask the customer whether they want the receipt, they’ll likely say no. After all, who really wants more slips of paper laying around? However, returning the receipt with a, “Here’s your receipt in case anything goes wrong.”

(Even better, show them you checked the order by saying, “I checked your order against the receipt, but here’s a copy for your records in case something was missed.”)

Why leave a receipt with this comment? Because it gets them to look at the receipt, which tends to remind them to tip you. Simple, right?

You can also get in the habit of writing a note on the receipt thanking the customer. In this way, the receipt becomes a way to personalize your service while also reminding them to tip you. It’s also a great time to remind the customer to close the order and rate your service (which they should be thoroughly impressed with by now). That way, you don’t end up with an order status that says “pending” by the end of the day.

Bonus: Increase efficiency

While it may not directly increase your tips, working on efficiency can help you get more done with your time. Besides that, customers who are pleasantly surprised by speedy delivery time are more likely to reward your promptness with a nicer tip.

Learn the roads in your city, even if that means spending some quality time with Google Maps. If you have regular customers, make mental note of how to get there—especially if those regulars generally give good tips.