OK I'm sure most of you already have excellent methods for scale practice but I thought I'd share mine. It's cheap and easy to do.
I realized at one of my lessons that I had gotten so used to practicing my scales "in order" that when my teacher just asked for them randomly I had a horrible time and flubbed completely. How embarrassing!
And I thought I was finally doing well with scales.
I decided I needed a method for practice that would ensure everything got covered equally but in random order to avoid these bad habits. So I came up with this:
Take 24 pennies (more if you are going to do multiple minors). Cleaner and newer is better.
Take a Sharpie or something else that won't rub off, and write a scale name on each one (12 UPPER CASE for major, 12 lower case for minor).
Keep them in a decorative cup or bag near the piano. When it's time to practice scales, mix up the pennies and draw one out - practice that scale and set it aside. If you don't play all M/m scales every day, then have a ziplock bag to put the "used" scales in until it's time to start over. Technically, as my husband pointed out, in statistics this is called "randomization without replacement" not totally random (which would mean you would put the penny back in the cup every time).
When I originally came up with this idea, I was trying to think of something beautiful to use but pennies are cheap and easily available.