Whatever the producer or director says is the law when it comes to actors. If you don’t agree with what you’re being told to do, don’t make a fuss when the cameras are about to roll -- or you risk being seen as unprofessional. Sometimes acting can be frustrating; the producer might alter the lines you’ve painstakingly learnt beforehand, for example. Learn to accept this and don’t complain.
When on-set, be aware that everyone around you is trying to do their job. When the cameras roll, don’t stand in the background chatting to colleagues -- it is distracting to others. Any necessary communication should be carried out in a whisper. Watch what you say, too. It’s fine to make jokes and banter during lunch breaks, but rude humor may offend those around you, while bad-mouthing another actor’s performance behind her back is a no-no.
Respect other actors and professionals while they’re doing their job. You don’t want to distract them in any way, and this includes holding back from asking them questions about their work or even asking for an autograph until you’re off-set. Act professionally at all times. Nobody on the set wants to hear about your private life or the state of your career while they’re trying to concentrate.
You’ll make an immediate bad impression if you don’t arrive to the set on time and ready to act. This means arriving in plenty of time so that you can get into costume and be briefed by the crew as need be. You’ll want to be as ready as possible for the scenes you’re in, so memorize your lines and read through the scenes you’ll be in beforehand, even if you’re in the background for most of the time. When the cameras are about to roll, ensure that you’re in the right place at the right time and listen to what the director tells you to do.
You may be issued props during your stay on-set. If so, ensure you keep them in good condition and are able to produce them when needed. With regards to other props on-set, don’t touch them unless authorized to do so.