"One must practice slowly, then more slowly, and finally, slowly."- Camille Saint-Saens
"If you keep your body relaxed, the body is in contact with the depths of your soul...is that clear? Because it's quite important." -Claudio Arrau
It takes a long time and calm, thoughtful study, just to play a simple piece well on the cello.
There are no short-cuts but there are long, arduous, dead end, time wasting ways to go about practicing. Obviously, you want to avoid them!
When you are practicing, you should always be getting a little bit better, minute by minute. If you are not, then you might not have chosen a small enough goal to focus on or you haven't chosen anything at all to focus on! Are you trying to notice more of what is happening in your sound (and how your body feels) each time you play a phrase or a shift? Do you have a no hurry attitude? Do you need a break? Try to do most of your practice without looking at the notes on a page. Memorize even 2- 3 notes at a time so you can focus on how you are playing and how you sound.
Memorizing
Unless you are practicing to improve your sight-reading, playing from memory is an essential part of practicing. If you are trying to decode the written notes at the same time as trying to play them beautifully, this is only possible if you have all the skills and awareness in place to do this. When practicing to progress to something more demanding of your current ability, you need to break things down and stretch yourself mentally.
Here's some excellent advice on practicing and learning from Robert Spencer, a Feldenkrais practitioner.
Patience obtains all things...
We usually think we sound great when we are first starting. That's because we have little idea of what we really sound like. (record yourself and if you listen carefully, you may be surprised at how you sound!) I talk to my students about the 4 stages of learning once they've reached number 3 for a particular skill. It makes them feel good that they are at 3 rather than 1 or 2 but it is only at this point that practicing may begin. When you are "consciously competent" you can execute the skill but you must focus on how you are doing it so you can do it correctly. At this point, doing carefully focused repetitions is the practicing so that at some point in time your brain will have made some neurological short-cuts and the skill will seem automatic.
Unconsciously Incompetent
Consciously incompetent
Consciously competent
Unconsciously competent
Here's something I made for my students on how to practice well:
Read this Brain Pickings article to learn more about the difference between how amateurs and professionals practice.
Having a love of music is the best motivation for practicing.
THE WORLD BELONGS TO THE ONES WHO TRY!
As a parent, I taught my 3 children that practicing was a daily responsibility. I usually gave them a string of chores so that practicing was one of the more pleasant ones. (If cleaning a toilet is on the list of duties then of course you'd be looking forward to practicing your instrument!) After a while, the child learns that practicing and learning an instrument is just something you do. It didn't occur to them that they could just stop doing it.