In general, my advice would be not to wear any kind of tartan cap with a tartan kilt. A solid color cap would look much nicer.

I have seen those who could pull off a tartan tam with their kilt, but I think most risk looking rather cartoonish.

As for tartan glengarries, I've only ever seen those being worn by girls, so they may look a bit feminine to many. I'd stick with a solid color.