We like to focus both on theological as well as practical items here, and a friend of ours recently posted a link to this blog: 5 Tips for Better Practicing. There’s some good tips in here, and may be worth passing onto musicians (and we know we could use them as well!).
As someone guilty of many wasted practice hours, I’m happy to help others avoid the mistakes I’ve made. Productive practicing also translates to many areas of life beyond music; so I believe that every student reaps long-term benefits from learning to practice well, regardless of how long their musical education lasts. Here are the first things I cover with my students on the topic of practicing.

Thanks for the link! I really appreciate Cardiphonia’s ministry — keep up the good work!
Thanks, and thanks for your good words! I look forward to reading more!