Depends on your key configuration and your play-style. Once you have figured out the best settings, all you need is to play a lot of different maps.
Don't play maps that were converted from other game modes. If don't know where to find Taiko maps in your playable range, check the profiles of players slightly above your rank and see what their top plays are, you can start by downloading and playing those maps. You will know that a map is made for Taiko when it's listed under Taiko mode in the Osu! interface (or by reading the difficulty: Futsuu, Muzu/Muzukashii, Oni, Inner Oni, Whatever Oni).
Never play the same map more than 3 times in a row (no buts and no "Just one more time! th-this time I swear I will FC... *bleeds and passes out*"), if you cannot FC a map after 3 tries, you are not ready for that map yet, put it in a playlist for later and switch to another map of the same or slightly higher difficulty (star rating difficulty).
Play with HD as much as possible. You prefer HR? you shouldn't, forget about it. HD forces you to read ahead, which improves your memory, and forces you to sync your hearing with the rhythm more than usual, you will definitely get better the more you use it. HR weakens your reading capacity (and hurts your eyes), I know from experience, only good for farming, not for improving.
Don't force yourself to play only Taiko, keep yourself "volatile" and keep playing other game modes too (standard and mania), getting used to different environments improves your rhythm reading further.
Last but not least: stamina. When you're tired you lose focus, your precision drops and you cannot read well. Play long maps, not converted marathon maps, there're many unranked long maps you can play, you don't have to worry about getting a bad score on those maps, you can play any difficulty you want, you can play even with HT (but avoid EZ). If you are not sweating, then you're not trying hard enough, you won't improve unless you actually get tired.
Your wrists will probably get an inflammation sooner or later, you can use anti-inflammatory creams when that happens, like the ones used in sports, just don't push your luck playing with an inflammation all the time, because if you do, at some point you won't even be able to lift weights anymore and then you'll need months to recover.
I'm not a top player by any means, but I made many mistakes and I learned from some of them.