One of the first maneuvers I learned when I started flying was an inverted flat spin. Flat Spins are a relatively simple aerobatic maneuver that can be performed with a fairly wide array of different airplanes. As long as your center of gravity is within a reasonable range and the throws on your elevator and rudder are adequate, with a little practice you should have this maneuver mastered in no time.
The movements to execute flat spins are used in other maneuvers such as Blenders, Pop Tops and Pinwheels. Developing good muscle memory for each direction will benefit you a tremendous amount when the orientation and attitude of the plane changes. I decided to include both clockwise and counter-clockwise rotations as I have found that having both in my tool bag has made doing exit maneuvers more fluid in many cases. For example, my preferred direction for rolling harriers is to roll left. When I am doing a inverted flat spin and rotating counter clockwise, the planes inertia pushes the plane into a right handed roll. This means I am required to stop the momentum and then get the plane to roll in the opposite direction. This brief moment causes the plane to lose lift. Yet, when I am doing a clockwise inverted flat spin and then transition into a left hand rolling harrier, the transition is fluid and looks seamless because the inertia is creating a left handed roll.