Modelling help, i have no idea what im doing.?

ive been offered a chance to do an all day modelling shoot at with modelconnect. this is an agency that connects me with other agencies such as storm to help me land a career and become a successful model. im not worried about the agency or anything because they asked me to bring my mum so im pretty sure its not a scam. im just worried about the actual day. i dont know what to do or what to wear. im 18 and 5"4 so i know runway is out of the question so im sticking wih photos. but im not sure what to wear or how to pose and stuff. i just dont want to make a fool of myself so any help and advice will be brilliant :) i just really need a confidence boost for it.