RIGHT HAND AND LEFT HAND TOGETHER.
Once you feel that you have control of each individual hand, waste no time in getting both hands into action. The bi-lateral demands of the chromatic harp are quite significant, and need to be cultivated from the very beginning. The most important thing to remember when you first begin to play with both hands is not to tense the shoulders up, and to continue breathing.
Begin with close order intervals, that is, with the thumbs at a third- place the left thumb on any note then place the right thumb on not the next string up, but the one above that. If the left thumb is on a C then the right thumb will be on an E. Now, very slowly and deliberately and evenly, both in terms of tempo and tone, play as far up and down the registers of the harp as you comfortably can. Use a metronome at this stage if you have one. If you don’t have one then get one. You should get into the habit of doing all of your exercises and particularly your scales, to a strict beat. You will be astonished how important an aide the metronome can be in helping the body to assimilate the music you are learning.
When you feel that you have accomplished that task with some degree of success, extend the interval by another string, that is to a fourth, then to a fifth and then to an interval of a sixth followed finally by scale passages at the distance of an octave. Remember, this is merely an exercise for the thumbs, not the way to play a scale, although there are certainly times when the playing of a piece requires entire passages to be played with the thumb, such as passages of stopped notes and passages using harmonics.