I agree with Roland and Casey. I generally warm up with scales, arpegios in the key of the tune that I am working on. Generally do about 15 minutes of this. I will work on my bowing at this time, and rythum of the tune I am working on. I will then start slowly if i am not familiar with the tune and gradually build up speed. This does not take place in one day. It is great if you have the tune you are working on, on your mobile device so you can listen to it over and over and over. This way it is in your head. My reading skills are slow, but I am getting better. I learn better by ear, so sometimes when I look at the music some of what I am reading does not jive with what I am reading. I agree with Casey, do not play the mistake over if you are aware you made one. By doing this it will be embedded in your mind and you will keep doing it. Back up play it slow right, over and over and over. It may take more than 4 times, but get it right. Yes it is time consuming, but as Casey says, each and everyone is still a student of the instrument, even the very best are and will continue to learn. We are just on different levels in time. Do not get discouraged. Perserve.