You'll be fine just be friendly and make sure you that you ask if you are unsure of anything.. better than looking like an idiot!
As long as you are OK with spending long periods of time on your feet then you will find the job easy, its not that hard.. Just try not to miss too many lectures due to late nights at work!
Another piece of advice would be to not wear heels as you will look a little silly and your feet will literally want to drop off by the end of the night.. wear comfy flats but not your favourites as they will probably get soaked. I would make yourself look nice i.e. do your hair etc otherwise you may feel a little rank with all the customers being dolled up! You are right in my opinion, looks do matter! Just don't get too excited when men hand you there numbers.. they like a woman who is giving them booze and will probably not even remember doing it in the morning! I used to work with a girl who always text guys who had chatted her up over the bar, and she always regretted it when they next came in.. awkward! I always would just tell them I am taken.
I hope this helps.
Best of luck! I am sure you will have a great time