Cut out your desired sheet music into the shapes that fit your nails. The best music to get a proper decorative texture is usually instrumental music, as the measures are not extended to fit words or phrases. It'd be a great idea to put your favorite song! :) My particular piece here was a violin intermezzo I had lying around. Also, try not to use double-sided sheet music as the music on the back tends to bleed through, especially if you are using clear nail polish as a base adhesive. If you need sheet music, be sure to check out my PianoFiles page:
http://www.pianofiles.com/user/1031439
I will be happy to send you any sheet you'd like! :) You can email or message me here directly instead of creating an account on PianoFiles.

Doing each nail individually, paint your nail white and place your cutout directly on the nail. They work best if they are the length of your nail, no longer. Starting with pinkies tends to be more convenient in the long run. *I use white nail polish because clear tends to absorb into the sheet music and turn it dark or grey, oftentimes blurring the music. Unless you're going for a darker effect, use white.* I apply pressure after placing them down for at least 15 seconds to set the paper in the nailpolish and have it absorb evenly with no bubbles.

Coat the paper with a coat (or two!) of nail strengthener. This is a really crucial step in making sure your nails last longer and don't peel from wear.

Coat your nails in clear nail polish once it all dries. BE SURE TO GO OVER THE EDGES, NEVERMIND PERFECTION. This is really important because it will seal in the edges so that if you wash your hands, or take a shower, the edges won't fill up with water and fray.

Allow them to fully dry for at least a half hour after that (depends on how long your nail polish takes to dry). Then you're all set! In the event that an edge of the paper begins to come up, just pull it up a little, dab some white nail polish underneath, and stick it back down. It wouldn't hurt to re-coat it with clear, either.