90 degrees to the nail, towards the center of the nail, and polished one by one.

The correct way to polish the nails is to polish the nails up and down with a coarse-grained emery surface before repairing the nails.
When it falls on the nails and polishes, the speed should be fast, and it should be finished by going back and forth.
Repeat the same action again, taking care not to injure the skin around the nails.