Should I address actors by their own name or by the character's?

Their own name, unless they are so far into character that they don't remember their real name. :) Don't laugh too hard, I've met people that don't come out of the character they have created...ever.

Just ask them some like to be called the character up until they are off the set...some not until they are done with the movie.....

i always call them by characters name .. infact i would say 75% of the actors i never know their real names ... if i see them years later that is when i find out their real names ..

yes, its to difficult to use their real names on the set, and it brings them out of character, remember, on the set, in front of the cameras, they are not acting, they are being...and being means that they are that person
Q

I think when you're giving instructions to actors on set, in front of the camera, or even during a take, there's no problem using the character's name, when off set, discussing things one to one, it's probably best to use their real name - you are meant to be developing a reasonably close relationship with your actors.

I don't think it's a hard and fast etiquette. I've seen and done it both ways, switching from one to the next, depending on what made sense at the time. As suggested before, see which you actors prefer. The main thing is when you are giving instructions, that everyone is clear precisely to whom you're talking.

Why not ask the actors when you have cast them or are in pre-production? I
assume they can tell you which they prefer and when?

Don't ask them what they prefer - tell them how you want to do it! You're the director after all, many actors need to be in an environment where they feel comfortable and free to do their best work, and a good way to help them feel reassured is if the director is a voice of authority - It helps to give the impression that he/she knows what he/she is doing. So just find the way you want to do it and stick with it - If the actor really objects to anything, you can be sure they'll let you know...

I call all of my actors "Pacino" so they will give their best, most passionate performances. :)

Just when I thought I was out, they pull me back in :-o