3. Know Your Goals - Baby Steps Are Good!
Even if you have limited time (e.g., 15 minutes, not 45), Know Your Goals for your practice session. They can be as simple as warm up and sing/play through one of the songs you're working on, or more demanding, like memorize the first half of a current song, or do research and complete your character worksheet.
Small goals are good! We all started walking with baby steps. Learning/mastering a piece of music is no different.