Dame Judi Dench's Rules when acting Shakespeare:
1. Remember it's a play, not reality. Well said - too many actors get lost in the moment at the expense their connection to the other actors.
2. Obey the meter. If you break the rhythm of the meter, you are betraying the natural speech patterns of human speech and no matter how hard you try to sound "natural" - it will sound "off" to the audience. Not to mention you will often times lose your character's emotional life if you betray the psychological speech patterns of the character.
3. Start scenes. Start your scene with energy and purpose! Before entereing, know what you want, how to potentially get it, and what to do when you get it...
4. Earn a pause. Too often, actors will pause their speech for thought/emotion, putting "air" into the words that is not necessarily needed. Speech in Shakespeare's plays comes at the speed of thought, so there's often no need to pause unless you earn it.
5. Don't separate. This one is subject to interpretation, but it may mean don't get too bogged down in the stress/unstress of iambic pentameter (don't get too sing-songy).
6. Drive through the speech. The energy that is needed is in the lines; use the words to drive you to the next thought, and then the next, to the conclusion. No need to contemplate any speech's meaning and lose the energy when it's as clear to the character as he or she works through it. The energy is in the words. Use the text to keep the energy of the character. This doesn't mean go FAST - this just means that you should speak through the thoughts the character has, not before or after them.
7. Antithesis pauses, up at the ends of lines. An antithesis should force an actor to pause, to draw the audience's attention to whatever contrast the line creates. Think of it as weighing out two options -- you want to make sure whoever you're explaining it to can separate one idea from the other. Shakespeare uses antithesis a lot, especially when a character is talking directly to the audience. "Up at the end of lines" is an admonishment not to swallow that final syllable -- especially since regular iambic pentameter wants you to land on the stress.
8 . Economy, simplicity, and negotiate with humor. Economy -- don't make your acting too complex, else you will garble the thoughts. Simplicity -- don't be all over the place - focus your emotional intention and action. Negotiate with humor -- nuff said here, find the humor in the text, even at its darkest point, there is always humor to be found.
9. You don't have to carry the message; the play does it for you. Again, divest yourself of the notion that you have to push too hard on the "message" or "moral" that the play communicates to the audience. Audience members don't like when you patronize them. Allow them to find their own unique meaning.
10. Trust the play and your casting. There's nothing more anxiety inducing than feeling that the play -- and your role in that performance -- isn't working on the audience. Unless someone walks out (and even if then, you've made them have an emotional response) there's no reason that you should feel that you need to second guess the play.