Hastening The Process
How should you train to hasten the natural process of running more efficiently as your fitness improves? Include a small amount of maximum-intensity sprinting in your training every week (something very few distance runners do). Testing the limits of your capacity to produce pure speed is a great way to stimulate neuromuscular changes that increase your speed, and by definition any stride change that increases your speed represents a technique improvement. Just 6-8 sprints of 10 seconds apiece will do the trick.
Next to running fast, running in a fatigued state is the best way to naturally stimulate stride refinements. Try to do three workouts every week than leave you moderately to severely fatigued. Two of these workouts should involve faster running (perhaps a tempo run and a session of intervals on the track) and one should be a long endurance run.
I believe you can further hasten the process of running technique improvement by simply paying close attention to how you run and making little adjustments in search of greater efficiency and power. A while back there was an interesting study done in which researchers determined that runners who scored higher on a general psychological measure of self-awareness were more economical. They speculated that more inward-looking individuals may also be more aware of their bodies when they run and thereby make more subconscious adjustments to their form that reduce energy waste. So get in the habit of really feeling your body as you run and experimenting with little adjustments. This habit alone may improve your running technique more than anything else.