I consider technique as a means to manipulate or manage the sound the instrument produces, with the least possible physical strain so as to avoid injury. Economy of motion is a key principle. Minimum wasted motion and the smallest and most fluid possible movement is desirable for maximum control. Achievement of relaxation and good posture is also the goal while developing technique.
I’ve heard people say that playing the harpsichord is all about ‘articulation’, which is the degree of detachment or legato between notes. I don’t think so. That’s just one of a number of expressive tools available to the player.
Playing the harpsichord is about using a great deal of variety and little surprises to create an interesting sound. Expressive elements include the use of different touches in different voice or hands (one part mostly legato, another mostly detached); staggering the plucks of notes written as if they were to be played together – by how much and in what order; length of a note (the longer a note is held the louder the perceived volume); the degree to which notes are detached or overlapping; silence; rubato, and more broadly the manipulation of time and tempo; the speed of the attack, from slow and gentle to hard and aggressive. The elements of expressiveness are good to remember when developing or practicing technique, so that you can bend the practice to the development of musical skills, rather than ingraining a metronomic regularity.
Below are the principle categories of good harpsichord technique development:
Scales – these are very helpful as an everyday practice to concentrate on as wide a variety as possible of touches, while retaining a well-shaped hand with no wasted or awkward movement. I practice two octaves in every major and minor key, hands separately, as many times as I feel the need, in a variety of tempos and touches. Hands separately for a number of reasons; to hear what each hand is doing most clearly, to give the other hand a rest, and because hands together scales, while common in piano literature, are pretty rare in harpsichord music.
Octaves – How did we skip all the way to octaves? And why? I’ve found that these help in the playing of arpeggios. Hands separately, just up and down one octave. Stagger the pluck ever so slightly so that the outer voice plucks first. Keep the fingers as close to the keyboard as possible and a relaxed wrist and hand. I think of the movement of the thumb as like a stone skipping over water, gently and in an arc moving through the notes it plays.
Then arpeggios in octaves, as connected as possible. The point of this is to condition the hand, especially the thumb, to stay very close to the keys and to remain relaxed, and to train the thumb and outer fingers to jump or slide gracefully in intervals of thirds and fourths.
Arpeggios – I work on each hand separately for the same reasons as in scales; I recommend two octaves and occasionally three octaves of all the three note chords. This is very much about variety of touch and the ability to go from a smooth legato to a sharp staccato and everything in between, in a variety of rhythms as well.
Trills – Obviously essential and more about these later. But I will stress the importance of developing what I call a vocal trill, being able to trill at slow speeds and with accelerando and ritard, not just a one size fits all trill.
Double thirds – I find these help generally with control, as well as being a skill required for the many places where they show up in the music. It is helpful to practice them both legato and detached, in triple and duple divisions of notes, and to play the higher note of the pair slightly before the lower note. Also, practice the higher note alone, with the same fingering, in order to achieve an unbroken melodic line. It is easy for the hand to develop tension, and important to stop when that occurs, rest and resume with a relaxed approach.
J.S. Bach – I include the works of Bach as part of technique development, even though they are so much more. I find the two books of the Well-Tempered Clavier to be immensely helpful in the refinement and application of keyboard skills, in particular Book II. I believe this view has been held by every subsequent school of piano pedagogy as well. These pieces are not only beautiful and intricate, and often difficult, but they develop an independence of each line and the ability to bring lines in and out of focus as the music needs.