5 tips for productive practice

1. You will learn more from practicing a small section of music than you will trying to improve an entire piece at once.
2. When diagnosing problems in your playing, always start with sound production. Nothing else can improve if you are not making a quality sound! (For us string players this means checking bow hand/arm)
3. Mindless repetition is not an efficient way to learn. Make sure you have a plan before you repeat a section. 
4. Once you feel you have improved a section, make sure to give your muscles an opportunity to learn what your brain has already figured out. This means repeating a section many times after you have made an improvement. 
5. While picky, meticulous practice is very important, we also need to give ourselves time to just play for the enjoyment of playing. After you have done careful work on a small section,  make yourself play a larger section (or the entire piece) without stopping.

Articles from the internet about good practice habits

• 10 Easy Ways to Optimize Your Practice
• What Mozart and Kobe Bryant Can Teach Us About Deliberate Practice