"Smoothness". If there was ever a blanket theme for me in riding, this is where I start from.
Everything you do on a motorcycle should have the goal of being done as smoothly as physically possible for you. This starts from the moment you swing your leg over the saddle, to the action of the controls, to the line you choose to ride, to the method you use to control your body while negotiating transitions, to the very moment when we stop the bike and finally dismount. It is my primary theme when riding no matter what the environment, from stop and go traffic in downtown Grants Pass to dropping 100 mph from my speed entering turn 7 at Sears Point.
I practice being smooth every time I am on a bike. I practice smoothly rolling on and off the throttle, smoothly applying the brakes, smoothly releasing them, smoothly moving my body and weight to the inside of the turn, picking my line of sight. Everything that has a direct effect on the control of the motorcycle is done smoothly as possible. Although motorcycles are inanimate objects, they react to us exactly as we treat them. If we grab at the controls or jump around in the saddle the bike is going to get even - usually when we want the most out of it during a panic situation - and will do its best to toss you off.
To show what I am talking about, over the years I have demonstrated this with students at the track in a clear physical manner. While standing in front of them, I ask which of these two methods of moving them feels best. First I strike them with good force on their shoulder. I can promise you nobody likes it. Next I push gradually but with a smooth pressure on the same spot with the normal effect of moving that person to the point where I can no longer reach them.
It is this clear with the control of your motorcycle. Force will be greeted with an equal reaction. Smooth, gradual input will be tolerated and accepted. Another active observation technique I use is to watch the front forks while someone is using throttle control or braking. Watch how smoothly the forks compress and extend. It should always be a smooth action like ocean waves, not harsh diving and extensions that would form a sharp peak and valley on a graph.
For me, this is the concept of smooth and neutral direction control in a nutshell. You should never stop practicing being smooth, not ever!