I recommend it, personally, but that's my hobby, and won't be universal. There are lots of drawing tutorials available for all levels of expertise and assorted styles and at varying levels of step-by-step detail, and it's more than a little easier to assess a ballpark of objective quality in drawing than it is with writing. If you like to write, you could do your own webcomic (although I don't know how well you'd react to keeping an update schedule, you'd be in good company if you didn't stick to one); that's a good way to get in regular practice and improve. If you don't like to write and have halfway decent art, it's not hard to find a writer willing to collaborate.