How do you do basic nail care?

I don't usually take care of my nails, but sometimes I get self-conscious about my cuticles. Also, since I tend to cut them really short, it's not really a good idea to get a manicure.

I don't do it now, but I used to have a habit of biting my nails when I was young, so they are a bit spread out. I've heard that to manage this, I need to apply nail polish to grow them out so that the nail beds lengthen and the width narrows. ^^....ㅠ What should I do to take care of my nails?