Try a typing game, there’s lots of them now in several genres. I learned to touch type in secondary school, doing the old fashioned thing of taping a sheet of paper over the keyboard (and typing under it) so you can’t see the keys. That works but I believe in the educational power of games, and it’ll be more fun.
Otherwise, just practice. If you use lemmy on mobile, try switching to desktop to type more. Start writing letters to people or short stories or anything that just encourages you to type more.