Many new musicians practice, but don't know how to practice effectively. One way to do this is to make a list, with your teacher, of what you should be practicing and for how long. I do this for my violin, fiddle, and viola students. Here is an idea, a jumping off point.
1. Tune your instrument.
2. Play with a big sound on the open strings ((1 to 5 minutes))
3. Play all the scales you know. Play them slowly, and if possible with a drone of the 1st note of the scale. ((1 to 10 minutes depending on how many scales you are playing))
4. Play any etudes you are working on. After you have played it pick one measure and spend time making it perfect. Play the etude all the way through again. ((5 to 15 minutes or more))
5. Now play any pieces you are working on. Go to the line, or measure that is giving your trouble. Look at it. Understand it. Play it very slowly, even slower, even more more slowly. Listen to youself. ((10 to 30 minutes)
If you practice the maximum I have given you it will be 1 hour, the least would be 17 minutes.