Fly plaid advice.

[David Thorpe]

"This guy" has some problems of inaccuracy. The plaid "simply folded and... ...worn hanging straight down over either shoulder" is a day plaid, sometimes called a laird's plaid, but most definitely not a piper's plaid, which by the way is usually pleated -- not folded.
It should be no surprise that he also advocates the practice of wearing different tartans together -- just one additional faux pas.

On one very unique occasion, I wore a plaid of a different tartan from my kilt. The kilt was my clan tartan and the plaid was actually a scarf of my mother's, in her clan tartan. The occasion was her funeral. The point here is that if you do choose to wear two different tartans together, it should be for a very important and meaningful reason. People who know proper THCD will wonder at best, and think you ignorant and/or foolish at worst, even if they do not ask.

THCD is very conservative by American standards, and is decidedly not about the bling, or how much costume you can hang on your body at one time. Whatever you do with it, do it with as much class as you can muster, with respect for a very proud and worthy tradition, or kindly don't do it at all.