This is what I do here in this video, there's a specific angle I try to get one side of my nails to be. A flat slope down towards the skin but not to thin, because I want the nail touching the strings, but not too much nail to cause catching. The third finger has given me trouble as it can be easy to file it too short, but you learn the needs of your fingers over time. Also, I don't want the nails too long, that's why I file the top down too, and then I like to smooth it out so I'm filing all over a little. I always have vaseline near me for lubrication against the strings. Sorry for no audio, I thought I was recording audio for testing the nail on the guitar but you can still see my process here.