>>40738168
So I'm actually big into nail care and can help here! I got big into nail filing to help me with nail biting and tearing during Covid, and its helped them out a lot!

I recommend testing different grits. The higher the grit number the finer it is, the lower the number is, the courser it is, just like real sandpaper.

I like to use a metal file (Its in pic related, my husband put it there after a guy broke the sword off my Tanjiro figure, it felt too fitting to not use it here lol) but my mom uses wooden files/emery boards because her nails are less healthy and thinner than mine.
You want to test around a bit, but generally, you want your grit to be within the 180-600 grit range and work your way from there. Do you know the grit your glass file is supposed to be at?

What got me to do a bit better with nail filing was start with more consistent nail clipping with clippers/scissors, and using the file to "Buff/Finish" it out and smooth it from the clipping, and then going from there, to smooth out the sides, then filing the top and underside to make it more "rounded" and less "blunt" from the clipping.

Before I give advice on the shape and length, can I ask what your job is and if you have any hobbies that might effect your nails? For example, I was a violin player for a large part of my life and that meant my nail shape and length had to be specific so I could actually get my fingerpads pressing on the string.