Just have a good attitude! Remember that everyone has questions when they start. Its okay to ask as many questions as you need, even if it feels silly. Also try to introduce yourself to everyone, customers included, and you'll feel like part of the team in no time

I think I'm 3 weeks into the job and my best advice is to just ask questions anytime you have one.

Everyone I've worked with has been absolutely fabulous in helping me remember things or showing me how to do something again.

The POS screen is a beast among beasts. There are soooo many buttons for things. Then there are buttons that open up other screens and those screens open up other screens etc. It definitely gets easier the more you do it but even baristas who have been there a long time will sometimes have trouble finding more difficult and rarely ordered things.

And remember it's just coffee. If a customer is being a dick, they're just a dick. You'll get sooo many other awesome customers. If you put out positive energy many people will proiect it back at you.

My advice for bad customers is just realize they're a joke. If you can, turn around and giggle and move on. If they're THAT bad, just remember you'll be able to shit talk them to all the other employees later and other baristas on here.