At our conference, I attended two workshops that both ended up on strengthening plot. Lisa Papademetriou (Don't you just love her last name? I do.), talked about being your own editor. She is an excellent speaker, engaged us immediately and set us to work. She asked us to make sure that our stories have a backbone, a structure.
Is there an inciting incident? What is the problem your character is facing?
Is there rising action? Is your character solving the problems and getting into new ones, raising the stakes every time?
Is there a climax?
You must be able to identify the parts of the story. As storytellers, we naturally place characters in situations where they get into trouble, but the important thing is to make sure the story is logical. It's not always easy to make the ending inevitable, yet surprising. But the paybacks are huge.
She's a huge proponent of outlining. I am too. I find that outlines help me to stay on track.
Michael Stearns also spoke about plotting, particularly on generating tension. Ways to this:
Add a clock. Deadlines of any kind add tension.
Hide the why of the story. Reveal slowly.
Take full advantage of subplots.
Know what's pulling or pushing your characters.
Take advantage of the fact that everybody lies!
Follow through on every action. Action leads to reaction.
Be as mean as possible to your characters. That's right. Hurt the bunnies.
Here's a helpful sheet that Lois Peterson made using The Writer's Journey by Christopher Vogler, Brent Sampson's Nine Steps for Plotting Fiction and the classic 3-act structure.