As others have said or implied, I file my nails as needed. But I don't cut them or use clippers. And how often? I let my guitar decide. I've found this simple piece of advice to work very well regardless of one's ability: If you can not easy find the point of contact, your nails are too short. If your finger is getting stuck on the point of contact, your nails are too long.
I do buff or sandpaper my nails every single time I pick up a guitar. Remember what we do to achieve great tone: The nail acts as a ramp for the string. This ramp forces the string down into the guitar producing a full, warm, and well-rounded tone. Another way of saying it is the string will leave the string gradually. But the chain is only as good as the weakest link. The tiniest of imperfections will cause the string to catch. This catching will cause the string to leave the nail abruptly and not force the string down. A thin and scratchy tone is the product.
Last edited by Todd Tipton on Sat May 25, 2019 2:21 pm, edited 1 time in total.
Dr. Todd Tipton, Noda Guitar Studio
Charlotte, NC, USA (available via Skype)