Be prepared for a series of assistant-type roles and , at the start be prepared to work as an intern, basically doing whatever needs to be done. Must check ego and sense of entitlement at the door. If you have training in a specific sector of the business (eg- camera dept., sound, lighting....) but little professional experience, be prepared to start at the bottom and gradually learn and work your way in, and up the ladder. Your hard work and personal qualities will earn you respect and that enables upward mobility, learning new skills, and opportunities to move ibto higher and more demanding (and better paying) positions.
The industry, in any sector, requires hard work, humility (especially in the beginning) and punctuality. Observe and take note of everything. Its normal to make mistakes at the start, but hard work and a great attitude allow you to keep working and improving your position.
Now that I've said so much about humility and hard work, don't let anyone take serious advantage of you, coax you into anything dangerous, etc..