I like to draw and paint. When I practise, I find reference photos to mimic still-life drawing. Every time I tell myself that I should practise (becoming a better type designer and letterer), I always get stuck as to how I should practise that. If you teach type design, what kind of exercises do you give to your students? As for the more technical aspects, I find tutorials on Glyphsapp.com and try to repeat the techniques inside the application.
In typography, I set type in Quark XPress to imitate, in facsimile, a page of old letterpress typography.
In digital type design, I’ve used an existing font as a benchmark, trying to make my new type match (and better) its character count and readability; for instance, my Pratt body text font was designed to match Utopia in character count and x-height—even though it is a quite different genre.
Another thing I like to do to practice my vector-drawing skills is to recreate existing letterforms by eye. I think continual feedback is an important component of practice — if you can learn to see when a shape or curve is not matching your target, you can keep tweaking the point/handle placement until you can see you've got it. No better way to learn how to create a certain kind of shape or curve than to trial-and-error your way into actually doing it.
Uh, interesting! That is a start.