It may or may not work for you. You may feel free to use any of my ideas that you choose to. I seperate my teaching into 5 areas and they must work on all five weekly. I have told them that even if they have an unusually busy week they can at least spend 2 minutes a day on each area. That would only be 10 minutes of practice.
Tone is the most important part of their daily schedule.
I instruct them to start with tone exercises every time they practice. At first I write out tone exercises for them. After they have done this for awhile, I have them purchase Trevor Wye's Tone Book. We also test weekly the number of seconds they can hold a middle B natural. It must be steady and with no vibrato.