Know what you want, then make it sound like that. This is how music works right? A statement so general is completely unhelpful. Or is it? I find that this statement is the starting point of real practicing. Any problem with a performance resides in one or both of those parts. Is the problem in knowing what you want, or in making it sound like what you want? If you ask this question thoughtfully, the answer may surprise you.
Much of the time, the problem lies in knowing what we want! We know what we like when we hear it (reactive listening), but often fail to have a clear internal representation of our goal (anticipatory listening). This applies at all levels of our craft, from phrasing, to tone, and even to intonation. When is the last time you imagined what an ideal cello tone sounds like, vividly and clearly? What about the ideal tone for a specific note in a passage? Or the exact C sharp you are aiming for, ringing like a bell in your imagination before you begin the shift? We tend to fall in the habit of completing a shift on the physical level, and then checking in with the ear to see how we did (and it all happens so quickly, we think it is simultaneous!) Unfortunately, this exactly reverses the tasks our mind and body perform best. Without a clear goal, our body is pulled in many directions by competing areas of our brain, and our conscious thought process hinders our movements. We confuse the desire to hit a shift with the clear image of the goal. We focus on the action instead of the outcome. Our conscious mind is terrible at moving our body, and our body is terrible at knowing the desired result.
I'm sure every cellist can remember a passage where they had trouble finding a note because it was difficult to hear (maybe because the shift was up a major 7th, or some other interval confusing to the ear.) Once the ear learned the passage, the shift became much more reliable. This principle can be applied to all areas of the cello. My shorthand for this is "lead with the ear". Your imagination sets off a chain reaction in your brain, smoothing the way for the exquisitely timed hand-off from muscle group to muscle group that can never be consciously controlled (not well anyway!) The stronger your imagination, the easier the task.
There is a difficulty with language in discussing this topic; the words "want", "desire", and "goal". I may desire to have a successful outcome, I want to hit the shift, my goal may be to be perfect. I may have a burning desire, like the heat of a thousand suns, to hit that shift. Even though my heart is in the right place, none of that will help (and may actually hinder.) This is because the goal is nothing that the body can use. It is too general, and in a way, greedy. The desire to hit the shift is based on my self image and carries a lot of baggage. So we can have a harmful (or at least useless) goal, or a helpful goal. Desire can be applied at a base level, in the moment (think toddler), or a higher level, driving the structure of our practice and how we order our thoughts. Helpful goals are specific, sensory, and vivid. Harmful goals are general, grasping and involve the conscious control of our fine motor skills. Learning to tell the difference is a big step toward mastery!
Imagine if you applied these ideas to all areas of your life!