Something I find myself saying a lot is "you don't practice with your ears." The first time I learned to play the violin, the strategy for practicing (as I understood it) was to lock yourself in a practice room and practice until you got it right. The really hard-core musicians spent hours and hours in there and often achieved a certain amount of status for doing so.
Instead of doing that, do yourself a favor and only use your ears as guides to tell you whether your movements are correct. As you practice, you want to concentrate on memorizing what movements you are doing. Keep refining your movement each time you repeat something--be better at The Forehead, or The Sandwich, or whatever you are working on. Your ears will tell you when you're improving, but you will also know you're improving by an increasing feel of ease when you play.
Visualizing helps me and my students learn music more quickly with better technique from the very beginning. Here's what to do:
- Pick a small section of a piece you're learning (say, 2 or 4 measures)
- Read through it without your violin (rest position), but try to feel your fingers in your mind, going down on the correct place on the correct string, as you read.
- There will probably be a part that was hard to "feel" in your fingers. Go back over it until you can feel all of the fingers. Note: if you can hear the music as you read it, go ahead and hear it and feel the fingers as you read.
- Now try to get the same feeling in your fingers as you play the section on the violin.
Once you know what the section sounds like, you can also close your eyes and do the same steps as those listed above, but just hear the section in your head as you feel your fingers. You can also do this while you lie in bed at night--sometimes I'll do this with complicated, fast scale passages and find that the next day they are much improved on the instrument.
If you're not used to visualizing, this will really stretch you. Take it slowly (just a few measures -- or even a few notes -- at a time.