Warm Up: To begin practicing correctly, a proper warm up is required.
Practice Slowly: New pieces should never be practiced at performance speed. You should practice the entire part of the music you are studying at the fastest tempo you can play the most difficult passage – then a bit slower.
Set Aside Time: Any practicing is worthwhile, but time that is reserved for practice is best because interruptions are fewer.
Quiet: Practicing in a quiet space may be difficult, but finding that sanctuary for practice time will improve productivity within that time.
Calm: Practicing should be done when you are in a calm state.
Identify Problems: Many younger students will simply play a passage over and over without stopping to analyse the music for problems. (Being able to identify problems and implement solutions in an organised fashion is more than important to your music education and independence of learning.)
Isolate Rhythmic Problems: Rhythmic problems should be corrected outside of the line of music.
Work Into and Out Of Problems: It is wise to work out problems in small areas. Once a problem is solved you should practice into the problem from a few measures before, then from the problem area forward a few measures, then from before to after the problem area.
Practice In Sections: Always practice your music line by line or phrase by phrase. The brain enjoys small bites of knowledge. (It is easier to process and produce when there is less knowledge being processed at a slower rate of speed. This way you will not forget what went wrong and where it happened.)
Everything: I encourage students to not only practice notes and rhythms but all parts of the music as they begin. Dynamics, articulation, phrasing : all this should be included from step one when you practice.
Practice Daily: Building good habits require daily attention. The mind likes routine and will take advantage of a daily practice time. The more time you leave between practice sessions the more information learned will be lost. Keep your study fresh and continually moving forward.