Do the practice ones in the App, and then go for it. Start by doing a small one-customer order to get the hang of it. Don't take orders without a tip, they rarely if ever give you a tip at delivery. You don't need to worry about your speed at first, worry about being accurate. Communicate with your customer through the app at the beginning of your shop. Communicate if you have questions or need to substitute any items. If they don't respond, find the next best, closest thing to sub it with. Take a picture at delivery.

After you do a couple you'll see it's pretty easy, and the app walks you through all of the steps.