I've been at this off and on for a couple of years, at least. Lisa has some great tips in her lessons, and I'll be picking up where I left off at maybe "Cross That Line." Sorry if I didn't get the title right.

Seems like one way to make sure a practice is constructive is to put a time limit of no more than 30 minutes on it, especially when you're first learning. If you're going to have some sort of technique breakdown, it's going to happen when you try to practice too long, and then you run the risk that whatever wrong thing you might start doing becomes a bad habit that you have to overcome.