tl;dr: Neal Stephenson (author of The Baroque Cycle, which he wrote entirely by hand) argues that writing longhand engages more of the brain and, done properly, doesn't cause the cramps people fear. He offers practical tips: use a fountain pen (or gel pen) rather than pencils/ballpoints to minimize force, choose paper with a bit of "tooth," use cursive, don't skimp on paper, and start with cheap pens and cartridges. He also dismisses common objections around left-handedness and ink disasters as largely overblown.