Plots are simple. I try to follow the KISS method - Keep It Simple, Stupid. If I spend too much time devising incredible plot twists, double & triple crosses, and 18 layers of political intrigue, I find that I have often wasted a lot of time, as the players will do something unexpected and avoid 90% of those twists & turns, or just charge through them.
Look at it this way - "Star Wars" (the first movie) is a relatively simple movie - young innocent (Luke) tries to save princess with help from a wise old mentor. What makes it a great movie is one of the great all-time movie villains in Darth Vader and some great NPCs - Ben Kenobi, C3PO, R2D2, - and some interesting minor characters like Greedo, the sand people, the jawas, Luke's aunt & uncle, etc.