Currently in my classes I'm discussing plotting. One of the things I've pointed out to students is that the best way to learn plotting is to put their hands on the plots of other people. Keep a journal of the books you've read, the movies you'ves scene, episodes of your favorite television shows, and even the action in video games you play.
All of those mediums have plots. Some are more apparent than others. Some television shows, such as a favorite of mine, HOUSE, are similar from week to week. HOUSE is especially formulaic, and the writers have even poked fun at it in different episodes. The thing is that the plot works each and every time.
As you read through the books, watch movies and television, and play your video games, make notes of where the action starts. What does the character have to achieve in the beginning? How does it become worse as the story progresses? Does the resistance the characters face increase? It should. Do the stakes grow ever higher? They should.
Map the plots you find in your entertainment. Make yourself aware of how the writers boosted your interest level (or lost it!).
You might be surprised at how many plot devices are similar. Most people worry that they're being predictable, but some stories have to head in certain direction and cover familiar territory. The trick is to do some sleight-of-hand, offer surprises, and create characters the reader cares about.
Learn plots, then figure out how to be innovative. It's hard to be innovative when you don't know what's gone on before.