Not quite the same as a novel

I wrote a screenplay once and almost sold it twice. However, when producers called my agent he was too busy trying to sell his own screenplay. He was insistent, pushy and the producers soon lost interest in mine. I found this out because he told me he was pushing his own. He was unethical, true , but he wasn't a liar and I laugh about that now.
Anyway, I'm trying it again. I went up to the Internet and found sites where you could read current screenplays that went into successful movies. I read 'Constantine', and boy have things changed. Not in the way of format, but in the writing itself.
On writing mine, I was trained to describe each character in detail, everything from a physical description to their age, their personality. This training came from writers who's screenplays were made into moves. Now, however, it's not quite done that way the same as the writing of novels has changed. In screenplays, you introduce the charcter with their age shown this way, (30) and explain them in a few words.
The main ingredients though haven't changed. There still has to be a good mix of narrative and dialogue, just enough to keep the story flowing. In Constantine there was more narrative than dialogue and I thought it was well done. But this doesn't always work. Other screenplays I've read have more dialogue than narrative, but they're character driven works.
Therefore, I'll just have to start my plot on file cards--that's how the plot is formed, on cards than can easily be inserted elsewhere in the story if they don't fit their original place. Then I'll have to figure if I want more action or more focus on my characters.
At any rate, it's a chore, but it's fun too, as writing should be. And maybe I'll never sell it, but I've nothing to lose and a lot to gain.

More to come later