One of my first produced plays was a coming-of-age piece that followed the friendship of three girls from age 5 through high school graduation, a sort of alpha/beta/gamma girl character study before those terms hit the pop consciousness.
The play dealt with serious stuff: the characters betray each other mean-girl style, take up with bad boys, and generally grow up and apart. Y'know, a drama.
Opening night, full house. Lights up, and you could knock me over with an Olsen twin.
Holy cats, I gaped, the audience is laughing. The good kind, too, laughter of recognition from the women in the audience, and so-that's-what-the-girls-were-on-about laughter of discovery from the guys.
Dang, I'd written a comedy.
Sort of. A bittersweet comedy, anyway ("sharply wistful" went one review). The audience loved the Wonder Woman lunchbox bit, the getting caught smoking scene. And these moments, instead of steamrolling over the darker sections, helped reinforce the drama of the play as a whole. Growing up, after all, is a mix of the funny and the tragic.
Learned a couple of key things here.
One: A little comedy helps any story.
Two: Get your work spoken in front of an audience to truly understand what you've written.
Just speaking the lines yourself, as you write? This will save you from the clunky phrase and inadvertent tongue twister, but you won't understand how the actors' back-and-forth flows, or, more importantly, what the audience will draw from it. Writing groups and classes are handy for this, since typically the participants take turns reading aloud each others' work, but getting actual actors to read your work is even better. These folks know how to take the words off the page, and your audience can give themselves over to listening and reacting rather than reading ahead or anticipating their own next line.
If you have warm bodies willing to read and others willing to listen, you'll be surprised at what you learn about your own script. Plus, for pure narcoti-- I mean motivational value, it's tough to beat.