Keep them moisturized, I highly recommend you invest in some cuticle balm and/or cuticle oil and use it daily before bed. I use ChG Orange Cuticle Oil, but in your case I'd recommend something like Lush Lemony Flutter instead. Also make sure to use a good fat hand cream too, because if your fingers/hands are dry that generally means your nails are as well.
Another tip is to always keep your nails polished with your favorite colors, as this provides some protection for the nails and it will also make you less likely to chew them when you're bored or nervous because - most likely - you don't want to ruin the pretty polish.
Hi, I am sorry for the malnutrition of your nails. To have healthy and beautiful nails, firstly,you have to red rid of the bad habit of gnawing them. And you can use some nutrient oil to moisturize the skin around your nails. Don't care much about them, they will grow long quickly, and then you can decorate them with what you like.