Wear loose fitting pants, if you have anything like light weighted sweats (thin not thick, you'll sweat so bad) and a a plain white t shirt, usually good outfit to wear. Running shoes, or even casual athletic shoes should be fine. Most Kwoon's I've been to want you to keep your shoes on unlike dojo's (culture thing).
Maybe stretch a little ahead of time, eat well before hand (mild foods usually better, when I eat spicey and go to class, my stomache gets upset) and sleep plenty good the night before.
Also notice if the students bow to sifu, and on what occasions they bow, and how they bow, if they do the full hung ga bow then let them teach you that first but they'll probably just do a basic hand in fist (don't know the name?) bow. They'll also probably bow when entering and leaving the kwoon if your sifu has a shrine/picture of your sigung in the kwoon.
kwoon: Chinese term for training hall
dojo: japanese term for training hall
sifu: your master
sihing: senior student, or possibly term for student instructors
sigung: your sifu's sifu.
sibaak: Your sifu's kung fu brother, you're kung fu uncle
That should be most of what you need to be concernced about. You won't need to bow if no one else is most likely. And they'll correct anything wrong your doing, don't be worried, go relaxed and excited.
