My teacher used to say that it's easy to consume an hour with the instrument in your hands but that doesn't necessarily mean that you practiced. Here are some tips for good practicing:
1. Open the case-- Daily practice is essential but sometimes the biggest hurdle is getting started. I recommend leaving the instrument out (assuming it's safe from little kids and pets) and ready to play so you can just pick it up whenever you pass by. Once begun is half done.
2. Slow down-- Most students play too fast. What's the point of playing it fast and wrong over and over again? Find the difficult parts and play them very S L O W L Y. Don't just practice until it's right, practice until it's never wrong.
3. Use a tuner-- Apps such as PitchLab, G Strings, Pano Tuner, or TE Tuner act like another set of super accurate ears. Use the tuner for very slow practice, and don't go on until each note is perfect. It's a great way to train your ears. Sometimes a millimeter on your instrument is the difference between discord and harmony.
4. Use a metronome-- A good musician must be able to hold a steady beat, without slowing down for the hard parts and speeding up in the easy parts. After you can play it with the metronome, turn the metronome off because you don't want to play too steadily-- certain spots might require give and take in time for musical reasons.
5. Scales and arpeggios-- These are the building blocks for most music. Know them inside and out and you can play practically anything.
6. FOCUS-- Pick a section of music and commit to playing it well. Think about everything your teachers and coaches told you while you practice.
7. Walk around-- Memorize your music and walk around while playing (cellists and pianists can't do this). Step away from your music stand and loosen up your body.
8. Multiple 30-45 minute sessions-- I find that it very difficult to practice a full hour without stopping. Take small breaks to clear your mind and relax your body. If anything hurts STOP, you are probably doing something wrong. You could injure yourself. Shake out your hands do some stretches and jumping jacks. Drink some water. Then go back to practicing.
9. Listen to lots of recordings-- You should know what the music sounds like in your head before you play it. Listen to good recordings to get a feel for the music. Sometimes it's good to play with the recording! But not always. Don't just listen to one recording, so you don't just copy one person. Luckily YouTube has a lot of free performances readily available but not all of them are good quality...
10. Understand the music-- Learn about the historical context of the music you are playing-- stories about composers are fascinating. Study music theory-- knowing about how each note functions and how it fits in the piece as a whole is crucial. A deeper understanding of how it all works and why it was composed will add depth to your music making. This is a good activity in between actual practice sessions and it is just as important to your final music making.
11. Find Motivation-- Having a reason to practice sure helps, whether it's an upcoming private lesson, chamber music session, orchestra rehearsal, audition, or live performance. You don't want to mess up in front of other people!
12. Make Music-- Remember that beyond the technical difficulties of instrument operation lays the incomparable reward of making music. It has healing power if you open up your heart to it. The human spirit has a special connection with music. Practice can help you get there.
This is by no means an exhaustive list. Does anyone have more tips? Leave them in the comments!