Regular practicing is always a good advice. The advice we had in music school was: at least one half hour of practice every day. This is the advice for most music instruments.
I usually followed this diet, I practiced 6 days a week, from 30' up to 2 hours. Sometimes skipping a day.
The teachers said long hour practices are unneccesary. 4, 6 or 8 hour practice sessions are really not necessary at all to make progress at music school.
Only conservatory students need those intensive daily study to make advanced progress.
What had helped me most was the C-system CBA teacher I started with right from the beginning, he paid a lot of attention to correct fingering and other details, right from the start
And this focus on fingering went on for the whole 10 years of my accordion study in music school.
Because they knew if you get it wrong from the start, your sensori-motori system, hand/finger muscle memory, will soon suck up all the wrong habits. And it can take a very long time to relearn the correct fingering habits.
Even when it's easy to understand you have to use other fingering for left and right hand, it is a bit of a personal struggle to get those bad habits out of your muscular/memory system.
With the accordion I was lucky to get it right from the start, thanks to the accordion teachers.
With the classical guitar, it was another story. I had been "playing" the classical guitar on my own for some years (using a mixture of staff notation and tablature), before going to music school and take classical guitar lessons.
I could play a little bit of guitar on my own, but when under guidance of a guitar teacher after some months my playing improved significantly (pivot fingers, better fingering, I could bind the polyphonic passages legato, nail care and filing)
Taking music lessons with a music school teacher is like going back to school, you have to do your homework on a daily / weekly basis. And you get an honest and live direct feedback from the teacher.
Needless to say I did not have the same discipline when "studying" the classical guitar completely on my own. I only tried to play pieces I liked, and skipped the études/studies/difficult passages

Sounds familiar?
