First, you have to hearse. That's obvious. Of course, no one teaches hearsing anymore. It's fallen out of fashion. So you'll have to teach yourself to hearse, which is how you get ready for a rehearsal, and you'll never have any idea if you are doing it right.
Second, begin apologizing to everyone who will not be in the rehearsal room, (hereinafter simply called "the room"). Those not in the room will never understand. The mania is particular each time. No one outside the room will understand the importance of the stories you tell about the room. No one outside the room will understand the vocabulary of the room. No one outside the room will understand why you want to get back into that particular room.
Third, your baby and your boyfriend and your favorite TV show are probably all outside the room. You'll miss them and two out of three of them will miss you. Pray for the right two.
Fourth, beware of connections. While the boyfriend and the baby and the TV show might not be able to get into the room, the room can leave itself and follow you around. It'll make you start to believe that everything in your life is connected to what's happening in the room. The lyrics to your boyfriend's punk albums will start to guide your text. The yogurt your baby eats will announce itself as the color your character's costume should be. The TV will explain how your show should end. Almost all of these seeming connections are dead ends. The room is just jealous of your life. But you never know. One out of a thousand weird connections is perfect and useful, that's what makes chasing them all down worthwhile.
Fifth, begin apologizing to everyone who's in the rehearsal room. You're cranky. You smell like energy drink and cigarettes. You didn't hearse right, so you're not as ready as they are—at least you're not as ready as they think they are. You're having trouble compromising. You're having trouble collaborating. You're having trouble remembering the difference between compromise and collaboration. You're checking your phone under the table to see if your boyfriend sent you a picture of your baby dressed up like a character from your TV show.
Sixth, it's already over. It happens so fast. And it's only as magical and as deep as you're able to make it by really being there, being prepared, focusing, loving with passion, arguing with love, collaborating without compromise, compromising on all the little things, recognizing the big ones, staying balanced in your personal life so you don't crash the room, engaging with the process and not giving a fuck about the product. The product lives only in the heart of the audience and they're only in the room for one glorious hour and fifteen minutes if you do your work right. Two hours if you're pretentious. Three hours if you're a fucking asshole who can't edit. And even then—it's already over. And it's time to start hearsing again.