When I'm playing this specific part of the song, the sound of my nails scratching the string when picking is very loud on the D string and a little less loud on the G string. My fingernails are picking the strings at a 45 degree angle. So what am I doing wrong? The person who made this arrangement didn't have those string scratching sounds in his cover.
If you are using your nails, it's better if your fingers are perpendicular (90 degrees) to the strings. If you have them at 45 degrees they will slide along the string hence the scratching noise on wound strings.
Without seeing your hand position and the state of your nails, it's hard to comment. Most folks who attempt fingerstyle playing have their nails WAY too long and thei picking technique is....Less than optimal.

Classical guitarists have this down pat. Tone production is part of the essential basics the student is taught from the beginning. Hand position, attack on the strings, nail care...Etc, etc.

You don't need to learn the whole classical guitar thing, but the basics of position and nail care will take you a long way.
Aside from technique, a large part of it also comes down to what you're actually playing on. If your D string is roundwound (though I imagine it can happen with flatwounds to some extent), but your G string is not, that'd explain why there's no such sound on the G string. You're basically doing pick-slides with that one nail everytime you pick a note there.

Another factor is whether you're using nylon strings or steel strings. Nylon strings will get scratchy from play when nails are used, but it takes a good ear to hear that. Steel strings will not get as scratchy, they'll get rusty. And even if you won't see it, you'll hear it.

The main problem, but also trick and beauty of, playing with nails when it comes to classical music. Is that you're more or less employing 4 violin bows. The thumb, and at least three fingers (some folks have used their pinky to pick). That means you'll also somewhat use those nails in the same way, but it requires the nails to be as polished as glass, and the strings to be near-perfect as well. After a while, with a bit of wear and tear, the extra non-musical scratchings and noises produced will become unbearable to listen to, and your tone will be dead and soulless.

So, while I wouldn't advise you to bend your wrist precisely 90 degrees perpendicular to your strings for ergonomic reasons (you will very likely hurt yourself at some point doing this), finding the balance between playability and tone will be something to look for. A slight turn or twist for specific runs won't be overly damaging, but also a particular way of striking. Quite commonly, when people play at a slower speed, they'll also move their fingers more slowly. Which will be slower pick-slides on that D string, and if you're using steel strings, that corroded G string as well. So one option would be to use only fast movements, but timed so that they're still properly fitted in the music. This way, your 'pick-slides' will be so fast they're hardly noticeable. And this type of technique does not need to affect your tone or volume, that can all be shaped by touch instead.

A last option would be to simply avoid using nails on steel strings but flesh, or use acrylic nails instead, which are supposedly more easy to take care of and repair. Either way, just keep shaking the puzzle until the pieces fall into place.

Good luck

PS: As a last question, I presume that you're playing the A and D strings with your thumb, right? Because either a shorter nail or a slightly different shaped (polished) nail can help a lot.
Wise Man Says: The guitar is obviously female, she's got hips, breasts... and a hole.
UG's Flamenco Club
Last edited by FretboardToAsh at Sep 27, 2016,