Question: How to file your nails properly
Options:
With a fine enough file you can file your nails even when they're painted and the finish will not be damaged whatsoever
Using any nail file make sure you file towards the center of your nail; your nails have a grain and to do otherwise can make the nail end ragged
Answer: Using any nail file make sure you file towards the center of your nail; your nails have a grain and to do otherwise can make the nail end ragged