I'm going to have to go all girly on you now and talk about nails. I play on nails, so that means I need to have good nails in order to play...if you don't play on nails then excellent & great stuff, you'll never have to be girly, just cut them off at the base and go!
Nails...I can offer a few tips - unfortunately the first one is "be born with good genetics for nails". My nails are quite strong, I can play on steel string with natural nails and although they do wear, they can take it. On nylon, well, I have to keep filing them down!
I've used nail oils, the stuff that is supposed to strengthen your nails and cuticles, meh, don't know if it made any difference. I don't bother anymore.
I shape mine fairly often - the moment there is a small nick in one I quickly file it smooth again. The little nicks can turn into cracks and rips real quick. I keep nail files all around the house so there is never an excuse not to keep them trim. Yeah, pretty girly, but if you "break a nail" <sob> you won't enjoy playing for at least a week, and even then you won't enjoy it!
When filing only file in one direction. Shape down the sides of the nail so that you don't let rips start through the sides. For goodness sake don't ever bite them! And fingernails are not screwdrivers!
If you are not blessed with good nails then try cutting them off to the base and play hard on fingertips on a steel stringer for a while until tough callouses start to form. You'll find that playing on callouses gives a good feel and sound on steel strings when you are used to it, and you never have to worry about breaking a nail. I triend this once, but I just didn't like it, so I've gone back to playing with nails on nylon. Nails are nice for that classical sound - even the non-classical sort of stuff I play.
To protect your nails further do things with your left hand that you normally do with your right. Open doors, scratching dried food of the babys high chair, etc - keep the right hand away from potential nail breakages. Wear gloves when you wash dishes. Don't play immediately after having a shower when you nails are waterlogged and weak.
This deals with thumb and 3 fingers on the right hand (I keep my pinky on right hand short, I don't pick with pinky so there is no need to look after that nail). On the left hand I used to cut them off as far down as possible, but I found that leaving just a tiny bit of nail stops your skin from trying to push up over your nail when fretting. I just cut left hand nails with clippers, I rarely bother shaping them.
Learn you nails too; my right middle fingernail has a ridge that grows through it making a weak point, right on the striking bitey part. I'm careful to keep that section of the nail smooth. My right ringy grows really fast but is prone to tearing through the side so I make sure I file both sides smooth.
If you have bad nails, maybe consider getting acrylics. I looked into it once when I was playing on steel, decided against it because of the maintenance. I think you'd only bother with acrylics if you were fulltime professional and playing on steel.