That's a beautiful tartan.

As for dress advice, generally it is accepted that we follow the same standards of men's wear. To that end try to break up the top half a bit to not look so monochrome. Try a tattersall with a contrasting striped tie. It is also an accepted practice to wear hose that don't match any element of the outfit. There are some really good practitioners of highland dress here, so you will get some great advice.