Set up a consistent schedule as best you can. Use class time wisely if you don't have enough time at home.
"Almost no one likes to practice. That's just the truth. We all want to be heroes, but we just don't want to fight the dragon. And that is understandable. Dragons have bad breath." --Wynton Marsalis
Always give best effort and have a positive attitude. There are varying levels in every group. Respect those who try their best and practice what is assigned. No one should ever feel inferior because they are starting at a different point than someone else. If you have a private instrumental teacher, they will be able to give you deeper insight and awesome skills. In a class of 30 where there is group focus there is minimal personal time.
Tip from Sara Bashore: I use M&Ms or Skittles to count how many times I play a piece. Every time I play it correctly, I eat a candy. I start with 10, and when the candy is gone, I'm done practicing that piece.
Try listening and playing back what you hear on the radio. Try writing your own song. Don't keep yourself in a box of only playing what is on the homework page. Go to the music store and get a music book that has a CD that comes with it.
Be prepared, focus on MUSIC, Listen, participate, No Excuses, Challenge yourselffinger through music silently what you didn't get to practice at home, be encouraging
With Instrument or without: Do you have to practice with your actual instrument? No. You can look at the notes and think how they would be played. The BEST possible practice is with the instrument. If that is not possible, try other things like air fingering, listening to music, and anything else can you think of that would be almost like actually playing or keeping your mind focused on music?