Brief #4 USING GOALS OR OBJECTIVES IN ACTING.
Your objectives are your goals -- what your character wants -- and your actions are the things that your character does to achieve those goals. Every acting teacher whose work I have read says that no matter what your character says or does, there must be a reason for choosing one option as opposed to another. The action or speech may seem stupid to you, the actor, and so you must try to understand the character to figure out why the character would say or do what s/he says or does.
Your character may have several objectives and try several different actions to achieve them. Often you will see an actor who seems "one note," or repetitive. This usually stems from either picking a single objective and trying only one action to achieve it, or from picking no objective at all and only playing actions that have no meaning, since there is no reason for them.
A simple example: I open the window. Maybe I do it because I am hot; maybe I do it because I want to speak with someone outside; maybe I do it because I want some fresh air; maybe I do it because I burned the toast and the smoke alarm will go off if I don’t clear the air quickly. The reason will not always be clear from the script, though, and you must study your character to understand why s/he opens the window.
A more complex example: You will probably find that most of the time you can find an objective in the script. Try to find the most concrete thing you can, though. "I want love" is hard to play; "I want Jim to tell me that he loves me" is a stronger choice. The reason that the second phrase is easier to play is that it is possible to come up with actions to accomplish it. Your character could try being really nice to him, or seducing him, or making him jealous, or whatever else the script holds.
Be careful, though. The most important thing about actions is not to overplay them. If the action you have chosen isn't helping you to achieve your objective, try another tack. Often, in real life, you will use several different actions in the course of pursuing a single objective. Try the same thing as your character.
Sometimes (again, as happens often in real life) there are characters who say and do the exact opposite of what their objective is, and there are also many different kinds of objectives. You may even find that your objectives change during the course of the play.
The worst thing to do if you don't know what your objectives or actions are is nothing. When in doubt, just try something, the first thing that pops into your head even. The worst that can happen is that it won't work, and you'll have to try again. Often, though, the choice you make naturally is the right one after all, or else it will show you what is! And after all, isn't that what rehearsals are for?
Based on work by Joshua Marchesi, San Francisco Shakespeare Festival