I have really dry skin and hair, and my nails are fairly brittle, so i have more than a few tricks up my sleeve for this kinda thing (despite being ftm... for some reason i still follow most of these)
As for nails, I use a thin layer of vaseline on them overnight and when it's absorbed i use clear nail varnish. People never notice it really (thank goodness. so masculine to have these flawless shiny nails). File 'em instead of cutting them too, it's something my mom always made me do. My dad does it too... they both have crazy strong nails.
I also take odourless garlic and apple cider vinegar tablets, though I've been lazy with it recently and it's already starting to fade... They're really good!
as for hair, conditioning it once a week for a few hours with a mask and conditioner mix with some oil really does miracles. I used to follow a really strict routine, and it has crazy good results, but it's high maintenance naturally.