What to wear to a casting:
Unless you are told what to bring or wear, it would be best to keep it simple. A casting is not a fashion show. Just wear a tee shirt, tank top, keep it basic, white, black, simple. And some jeans, or shorts. High heels are a must usually.
modeling casting extras: bring a hair tie or hair clip, for things like close ups or the eye casting I had the other day, the casting directors want to see your face, not your hair covering it.
Bring a photo that matches the job. For example: If they are looking for a runner for a fitness shot then, even if the picture of your self running isn't on your compcard, bring a photo with you of you running and staple it to your comp card. You should try to SHOW as best as possible that you are right for the job.
Not all agencies will give you stickers to put on the front of your compcard as the contact number. So keep a list of the agencies numbers you work with handy. So you can write it on the card.
Keep makeup simple and natural, nothing crazy/ no fake eyelashes needed. Just be you.