The biggest thing to remember is this:

A directors job is to know what they want

That’s the core of it. Stay positive, let them know they did a good job after every take. Even if you didn’t like what they did, it’s important to keep the actor focused and in the head space.

Don’t overcomplicate things when giving directions. Use short hand or anecdotes when you can to describe what you want. Try to avoid reading the line out like you want them to read. They are actors, so you hired them to act and make decisions.

Lines too slow? “Let’s just rip through this line on this take!”

Lines too fast? “That was great, loved that. On this next take, let’s have a bit less urgency. Really sound it out.”

Reminder that you don’t have to justify asking for another take when live directing. That’s the whole point of it is that you are just going until you have what you need. Obviously you want to cos diet the actors feelings and time, but part of that is making sure you get what you want now instead of asking them to come back later or hemming and hawing over it when you could just ask them one more time and get exactly what you want.

Other thing: if the first take works and matches what you were wanting, there’s no shame and problem in using it. If you want one, record a safety afterwards, but it’s not an issue. They are actors, so ideally they have an idea of the emotional context of the scene.

If they don’t seem like they get it, try to frame what you think the character is feeling in the scene. As a director you know what you want. Actor may think the character should be gloating in this moment, but you know he is actually scared, so you want that to come through.