I read this book despite writing a stage play rather than film script. I found lots of useful advice in it, eg
What is each character risking in your story, what are the three obstacles each faces, that a story might have a main character drawing one moral and a secondary character drawing an entirely different moral, try to make each scene tell a truth about the theme, all the main characters should in some way reflect the theme, you want bad luck for the hero, and good luck for the anti-hero. The bad guys get all the lucky breaks. If the villain makes mistakes, they are forced errors because the hero is harrying him right and left and he blows his cool. The hero should come up with a clever solution that would work in our world Hero and beloved should not get along until the final scene - or not Characters need to be opposites. If the hero's mainly intellectual, then the heroine should be mainly physical so they get on each others nerves but also so each can do something the other can't. He's practical but uncontrollable, she's romantic but controlled. Make a secondary character strong rather than weak so they can give your hero a maximum of trouble. If they can't be strong, they should be devious or mysterious. What makes a character feel real is specific, unusual details that the audience couldn't predict.
Tiptoeing through a myriad of information on screenwriting, I stumbled upon Crafty Screenwriting. This is a truly a terrific book for someone starting out in this business. I found it to be extremely well written and laid out - Alex Epstein clearly knows his stuff, I can not recommend it highly enough!