If you're writing a musical or a "play with music," if words are to be sung, they need to be set apart from spoken dialogue. Lyrics are written in ALL CAPS, but in all other respects, lyrics are written in dialogue format. Some writers double-space between stanzas (I do below), some don't. Go with whatever is the easiest read.
ERIKA (speaking as if to a young child) What do you think of your new school so far? (beat) Let's go - the bell rang five minutes ago, and you don't have a hall pass. (Erika pulls Skeeter to his feet, but he breaks away.) SKEETER THE BELL HAS RUNG MY BELL'S BEEN RUNG THREE TIMES ALREADY THIS MORNING OR WAS IT FOUR - I'M BARELY THROUGH THE DOOR AND I CAN'T TAKE IT ANYMORE I DIDN'T ASK TO BE IN HONORS MATH OR FOR THAT GIRL TO CHOP MY LUNCH IN HALF AND LEAVE ME FOR DEAD WITH THE FOOD CHAIN WRAPPED AROUND MY HEAD
If there is spoken dialogue in the middle of a song, just insert them on a separate line in mixed case between the lyrics, not separated by any blank lines:
ERIKA It's a replica. I wanted to get used to it. You can't just swing this thing anyway the wind blows. A GAVEL IS AS PRECIOUS AS A RAIN IN THE SAHARA YOU MUST SWING AND BANG WITH VIGOR AND LET NO ONE ELSE BE FAIRER
Stage Direction Element
Indent stage directions (except for At Rise directions) 2" from the left margin, and let them wrap at the right margin.
Stage directions always follow a blank line, and are either inserted single spaced within dialogue or on their own, between speakers, preceded and followed by a blank line. A format for stage directions is included with all script formatting softwares, making these transitions easy and headache-free.
Your stage directions are just as important as your dialogue. Remember that your reader will read them first, so make them concise and as readable as possible, perhaps even entertaining.
The Rules: Do not try to direct the play from the page by telling us what the character should be feeling or by giving abundant line readings.
Some writers like to write stage directions in complete sentences, while others prefer phrases. Punctuate accordingly. Whatever you do, use the active present tense.
COWGIRL I could suck one. I could suck one for an entire day. (finishes looking through the backpack) Where is it? (Cowboy pulls a tiny piece of meat from his pants. He puts it in his mouth and tastes it.) COWBOY Pork.