Don't self indulge, remain the actor until you step up to the camera. As actor you can listen to instruction, but not in character . Always consider the audience. Make something go on, you are hired to do something interesting. Audience won't sit and just watch conversation.
Audience wants worthy opponents.
Movies are all about behavior , play it through, not just dialogue. Don't go to the next line , there are no next line. Memorize lines, then forget them. Audience doesn't care about your problems, only the character. Do acting all on impulse .