To learn a musical instrument you must learn to master many physical skills. Your brain is reading notes on a page, while your fingers are contemplating which keys to press, all while your lungs are taking a big breath to blow through your instrument to create a sound. A music student's job is to excercise those skills, remember what you've learned, and have fun in the process!
Helpful tips for your practice session:
Warm up carefully. Warm your embouchure (lip & mouth position) and instrument for good tone production.
Select a time of day that is free from interruptions and use this time each day.
Choose a place to practice that is free from distractions
Set a goal for the session: a scale; an excercise; specific sections of a piece; or even a measure that is giving you trouble. Work on it slowly, then build up to speed gradually. Before leaving put it together with the rest of the line.
Repetition of a problem area reinforces muscle memory.