Unfortunately it's now 2016 and Apple still don't provide an easy way to do this, but one option would be to try Tap Tap Send. I built the app a few years ago to solve this exact same problem, and have recently given it some much needed TLC.
With Tap Tap Send you simply bookmark the people you message the most, then enter the messages you might want to send them. Now, next time you need to fire off a quick message just: Tap to select a person, Tap to select a message, Tap send, and you're done.
Here's a bit more about it — website, or check it out on the App Store.