I just got a new job waitressing, but it's not going so well?

i just got a job as a waitress in a sports pub. i went through a grueling training session for a week long and i also had to take multiple drink, menu and alcohol sales tests just to be prepared for the restaurant's opening. last night was my first real night on the job. i worked for 10 freaking hours and only made $40 in tips by the time checked out. we were super busy and i ran my tail off, but half of my tables were just dudes who ordered a beer and left. not that i mind working hard, but i have friends who are waitresses and they make a heck of a lot more. also this was the restaurant's second night open to the public so there were still some gliches that we need to work out. for example, no one told me when the grill shut down last night so i put in food orders after the kitchen had closed. hello, i think it's kind of important that you tell me when the kitchen closes. i got in troube with the manager because one person told me it stayed open until 2 am. i feel like i'm going to be fired anyway. not to mention, i put that i could only work 20 hours a week and they scheduled me for 6 days this week (at least 6 hour shifts). i go to school full time and i cannot fail out because of some job. i know jobs are hard to come by but i know i can find another job with time. also, i'm living with my parents and while i want to move out, if i don't have a job for a few months, it won't make me homeless or hungry. i feel like this job is not going to work out. what do you think? no one is communicating well and i'm getting frustrated.