The polka dot pattern on the dress makes so many different pixel layouts possible, so put some thought into what areas you'd like to light.

On my dress, the pixels reach comfortably from one polka dot to the next if I go in a diagonal pattern along the print, but if I try to span two columns of polka dots (and go horizontal) they just don't quite reach. So, diagonal it is! 

These pixels are pretty sturdy, but I still wanted to avoid putting pixels in areas where they'll be under a lot of stress. I avoided the seat and back area altogether, so I can sit down or ride in a car in this dress without worrying about putting too much strain on the pixel strand. I also avoided the yoke area around the waist, since I may want to add a belt or waist cincher there -- and areas that get flexed a whole lot are in more danger of breaking.

I kept all the pixels in one long strand, so I didn't have to do any soldering. You can run about 300 pixels in a row before you need to power-inject, so this keeps everything simple. My dress has 216 pixels, so it fits nicely within that range. If you have more than 300 pixels, consider using multiple data pins and shorter strands, or injecting power further down the line.

It's possible to turn some of the pixels off in the code, so if there's a run that goes past a place you want to stay dark, that's no problem - do what works best with your vision. 

I started with pixel 0 near the waistband, so I can attach the controller and battery there within easy reach. I then zig-zagged up and down one side of the dress, following the pattern. This dress is pretty well matched along the seam line which made this layout look great.

I then went along the lower back and under the zipper, then repeated the sequence on the other hip. I ended up near the waistline, and ran a couple pixels up through the yoke and zig-zagged across both cups, hiding an extra (darkened) pixel in the center front at the solar plexus.