hi. i work in the "food service industry" too. i tend to be more introverted too and am nervous in the beginning of a new job.

it takes time to get used to everything! especially in a busy place.

customers are rude and mean. i am amazed at how people think it is ok to be rude to us-- who are just people trying to do our jobs and yes, sometimes make mistakes.

i used to get nervous like you, but here are a couple things that help me.

1) i have a set of "lines" that i use if someone is getting rude. if they don't respond to my lines/questions, i say "please wait why i get the manager."

i found that having lines prepared removes the emotional upset i start to feel. i just move into prepared statements.

2) practice the lines and anything else you say in front of a mirror. practice saying it loud, so that you are confident with what you say.

3) ask your boss if there is anything he/she notices that you can improve. sometimes talking to the boss and asking how to improve so you do a good job helps them look out for you.

4) find a coworker who is cool and ask them what they do to relax. just having a "work friend" might help.

it gets better with time. good luck!