Here, I used a light brown nude (base coats underneath), then did a stripe of O.P.I.'s "Crown Me Already" on each nail. I was able to do this freehand, as this sparkle polish is very dense, and can easily be guided to where you want it. Another thing I like about this polish is that it can easily be touched up while it's still wet; just take a q-tip and touch up the lines for a flawless look! If you're using any other polish however, I'd recommend using another tool to help you draw the lines.
TIP: if you don't want to purchase any expensive nail tools to help you do this, an old liquid eyeliner brush works great for nail design! Just sterilize it and clean off any remaining liner, and it will work perfectly to help you draw on these lines!
This is a fun way to make your nude polish a little more interesting! Don't be afraid to play around with different colour nudes or sparkles, although I do recommend sticking to gold, silver, or more subtle sparkles to avoid a look that is too crazy. And don't forget your top coat!