Usually I do this with twenty things, but since I'm typing this up while preparing for NaNoWriMo, we're going with thirty, one for each day of November.
This step is really simple--think up and write down thirty things that might happen in your story. These don't have to be major things; some minor actions and happenings are still important to the overall story.
Now, don't go as simple as "Bill wakes up." But something like "Bill answers the phone and hears an unexpected voice on the line" could work. You might not know just now exactly what he hears, but if you know that somehow him getting this phone call is going to be important, go ahead and write it on your list.
For now, you don't need to put these in any order. Just get thirty things. If you can, do write down something that can be part of an opening scene and something that can be part of a closing scene. Something that could be part of the climax would be great if you have an idea for it. Also remember that story needs flow, so there should be some really intense things on your list and some things that are smaller and calmer. Give yourself a good mix to work with.
After you get thirty things written down, you can transfer your items to index cards and start playing with the order. If you can't get thirty things right away, write down as much as you can, and start playing with the order until you start getting a story flow that you like.
These thirty things will give you at least one small scene to write each day in November, and using these as jumping off points every day will lead you to more story elements that you want to add in.
Enjoy finding your story pieces! See you back here in a few days for the next step.