You know your piano player friends who practice their basic piano scales daily even though they're already well advanced and can play Rachmaninoff like no one's business? It may seem absurd to need to do such simple practicing at all, but scale exercises are the best thing you can do to keep those fingers sharp and fast when playing a song.
The simple principle applies to playing the guitar, as well. So why not sharpen those guitar-picking fingers by playing a popular scale used in rock and blues music? Check out this electric guitar tutorial to learn how to strum the rock/blues scale, also known as the pentatonic scale.