I find that nails should always be clean and neat. It gives other people a first good impression, that you are a well-groomed person. So since this is very important to me, I have three rules.
Rule number 1: Never chew on your nails. And when I write that, I really mean it! In my eyes it is disgusting when your nails are gnawed, out of shape and maybe even bent. So if you want to have nice nails, then you will have to stop that habit.
Rule number 2: Make your nails strong. I promise you, that everything is much easier with strong nails. If they keep chipping and breaking off, it will be just disturbing and strong nails can prevent that. There are alot of different nail strengtheners in the form of a nail polish, that can help.
Rule number 3: Choose a nice nail shape. There are all kinds of different nail shapes. If you have a favourite one, than go ahead and file your nails like that. It gives a whole new different look, when nails are squarish, stiletto or oval.