I can remember not being able to play an etude, and trying to solve the problem by "just practicing it more." Aimlessly performing the difficult music over and over again, only cementing in the problems. The most important practice habit of all is to have clearly defined goals.
When you can feel Practice Monster coming to the surface, take a break to ask yourself, "What am I supposed to be practicing right now?" If you can't answer that question in one short sentence, you should evaluate what you are working on, and find a way to clearly state the goal. Try stating the problem, and then some simple solutions:
Problem: I cannot play the measure with the ornament without losing the rhythm.
Solution: Practice playing without the ornament, and then slowly add the various elements of the ornament, one by one.
Practice Monster thrives on self-sabotage, and disorganization sets us up to fail before we have begun. Clarity of purpose keeps us on task, and the time spent working goes quickly and smoothly.
Unstructured practice can be fun too, and for many of us, it can be an important part of the creative process. (More on "Rampage Mode" in a future post.) Just remember to keep asking yourself, "What am I practicing, right now?"