Did I say unwritten rules... well unfortunately I had to learn them the hard way. So I am sharing these rules with you in hope it may save you some embarrassment when you first start out.
Do NOT stand in shot!
Well this may seem like an obvious one but I can assure you that on my first day on the job I must have stood in shot at least 10 times. I can also tell you that as lovely as most photographers are they do not have time for a bumbling assistant with their bum, left leg, dirty shoe etc ruining their shot.
When you start out and are trying to get to grips with your role it can be hard to know where you can and can’t go. The best thing to do is always try and be aware of where the camera and lighting stands are and generally avoid the area unless specifically asked to move something. If you don’t know just ask before you walk near the camera.
Do NOT knock or move the camera!
The quickest way to piss off a photographer and stylist is to knock the camera. One of the many skills needed to be an assistant is serious ninja moves. It’s not unlikely that you will find yourself in a small space surrounded by lighting equipment, carrying cups of tea and holding scissors in your mouth whilst trying to navigate around a tripod. My only tip is to think of that camera like a grenade. Give it as much room as possible. And if you do accidentally knock it be prepared for the aftermath. If the camera is moved it might mean reshooting a whole set which could cost the stylist half a day of work. SO BEWARE.
Shut yo' mouth shut!
Its probably best not to comment on the images unless you know the stylist very well. My belief is that everybody on set is equally integral to the shoot and I always welcome comments on my shots (apart from one time with a very involved courier) but not all stylists are the same. As an assistant no doubt your aim is to become a stylist and I’m sure you will have lots of opinions but generally on most shoots they are not welcomed so 'keep yo' mouth shut'.
Know your place.
Like I said I don't agree with this mentality but it will serve you well to understand it when you first start out. You will quickly learn that there is a hierarchy on set. With clients, art directors, stylists and photographers at the top and set builders, couriers, lifters and assistants at the bottom. Is this wrong YES. Does it happen YES. My best advise is to be a sponge. Keep quiet but take everything in. If you would do something differently note it down. One day you will be a stylist and all these things will help shape your work. One day you will have an assistant and you can treat them how you would have liked to be treated and I'm sure you will gain alot more from them and the experince.