1) Find a friend who is really into storytelling. If you can't manage that, modify a Tickle Me Elmo to artificially replicate human sentience.
2) Either rent or go see a movie. Now, your choice of movie is important. It can't be a complete joke or it defeats the purpose of the exercise, and it can't be practically perfect either. Find something that's pretty flawed but has potential.
Now your mission, should you feel obligated to give it a go, is to do it better.
Deconstruct it, discuss what worked, why it worked, what didn't and why it didn't. Then discuss how you would fix up the bits that don't work and improve the bits that are already there. Pretend you've been asked by the studio to perfect the film and that you have all the resources you need to do it.
Why? Because if there's one thing Mutt and I have learned over the years it's that you learn a heck of a lot more from the films that get it wrong than the ones that get it right. It's like gravity; If it's doing it's job right then you don't really think about it.
This exercise helps to build up your problem solving abilities and expands your knowledge of pitfalls to avoid. That and it's really, really fun to do. I think Mutt's version of the Felix Felicis sequence from Harry Potter and the Half-Blood Prince will go down as one of my favourites in Harry Potter history... even though it never actually happened.
Just remember, it's really easy to find faults in the finished product, especially when you're coming at it from the outside. It's not so easy when it's your own work and it's in development, so be nice.