Voicing will go a long way toward defining your sound as a pianist much like a sax player gets known for a certain tone or a vocalist has a certain quality. The 3/7 4-note rootless voicings are an essential mainstay and go a long way in achieving a framework for basic improvisation and other more complex voicings. It is the family of chord voicings that is probably the most important thing to get down in order to start to be able to comp over lead sheets. Once you start to play them you will recognize them everywhere from Bud Powell to Bill Evans.
These voicings follow a rule: avoid the root and outline the 3rd and 7th adding other necessary notes that are implied by the melody. In the simplest form this is generally a 3 5 7 9 or a 7 9 3 5. A good way to begin to get these voicings in your hands and see how they work with each other is to use the circle of fifths to cycle the ii-V7-I progression through all keys using one of the two voicings above as the starting point and rotating the voicings keeping either the third or seventh on the bottom:
|3 5 7 9 [F,A,C,E]||7 9 3 6 [F,A,B,E]||3 5 7 9 [E,G,B,D]|
|7 9 3 6 [C,E,F,A]||3 5 7 9 [B,D,F,A]||7 9 3 6 [B,D,E,A]|
The first thing you notice when playing these voicings through the circle of fifths is that you are not moving around much. This economy of movement frees you to think about the rhythm of your comping and your improvisational lines. These voicing combinations also create very strong voice leading (the perception of a “horizontal” connection between the chords) and emphasize the resolution of cadences within the progression. In other words, this is why these voicings sound good.
There are many possible mutations of the 3/7 voicings. Play with them and see how it is simple to create augmented, half diminished, b9, #9, when necessary. You should practice playing these in the right hand with “shell voicings” in the left or playing them in the left hand while playing the melody in the right. For simple two hand comping, pull the 5th out of this voicing and play it in octaves above the left hand or add other missing chord tones or simply the root in octaves.