I have natural Blonde hair and im dyeing it dark brown/red. What highlight colors would look nice in it?

I have a round face (if that helps) also I don't want blonde in it. The color is a a dark brown almost blackish with a red tint to it (not super dark but still dark) And i can't decide what highlights to put through it so that its not plain, ANY AND ALL help will be gratefully accepted I have natural Blonde hair and im dyeing it dark brown/red. What highlight colors would look nice in it?
straight red high lights would look so good. I used to have that. and part your hair on the side that takes away from your round face!!! it makes a big difference!I have natural Blonde hair and im dyeing it dark brown/red. What highlight colors would look nice in it?
black or brown