If there's a specific area that I want to target, then I try to find time to sit down and just draw a bunch of the thing and do some studies. I recently did this with both arms and legs, for example. Trace several, sketch several, trace over some muscle diagrams, etc.
I don't do much general practice, although I probably should. I'm in the camp of people that looks at the projects I'm doing at this stage in my creator journey as "practice projects" so I try to just look at the whole process of making my comic as practice of sorts.
That said I've recently tried to get back into doing some gesture drawing warm ups and have been thinking about trying some of those wrist warm ups that an earlier reply mentioned as well (lines, circles, line weight control/variation, etc. )