"He who stops being better, stops getting good" - - Oliver Cromwell

4) Practice is NOT optional:

You may have believed when you enrolled your child in guitar lessons that it was a half hour a week commitment. Not so! Studying a musical instrument requires a daily commitment. I expect that each of my students will play his/her instrument at least six days a week. A half hour a day is a bare minimum. There really is no other way to progress. You can't "cram" for a guitar lesson and, believe me, I can tell.

You must deliver the message that practice is not optional. It is a part of what your child signed up for when they decided to take music lessons. It is not something to “find” time for when there’s no homework, soccer, friends visiting or whatever. This is homework. Make it a part of the student’s daily routine. As the parent you must be the “enforcer”. If you don’t want to do that, you should probably consider a different activity for your child.

Find a time during the day that works for practice. Whether it's in the morning, after school, before or after dinner doesn't matter. What's important is consistency.

I want my students to play what they wish and I attempt to give them the tools to do that. To that end, their daily practice must include lesson material. They have a list of things to do for the week and should play each item on that list at least three times each and every day. If they don't, they will not progress. Listen to them practice and see if it matches their list. If they want to play other things, that’s fine too. The more the better but the lesson material must be a part of it.

By the way, three times a day is only the minimum to make some progress. If a student really wants to get better sooner, they should do more repetitions. There is no substitute for repetition.