I think one of the best ways to improve your flying --- and avoid picking up bad habits --- is to fly with other pilots as much as you can. Rent a plane with a pilot friend -- you fly one leg -- he flies the return.
All through training you are taught to fly solo. You get the occassional demo from the instructor --- but in general --- you don't see other people's technique unless you fly with others. You'll pick up lots of little things by watching others. For example, you may have always firewalled the throttel in 1 second on take-off and no instructor ever said anything about it. Flying with a "smooth" friend --- you might see that smoothly advancing the throttle over 4-5 seconds doesn't cause any appreciable increase in T/O roll --- but is a hell of a lot easier on the engine. There are a hundred little things you can learn by flying with others. Go for it.