For this one, for example:
1.- Wear a tartan shirt
2.- pull your hair (or just the fringe if you have) back, so your forehead shows
3.- You can use wool, felt, thread, or whatever seems appropiate, the color of your eyebrows, use a glue that won't tear your eyebrows off when the party's over, and carefully glue them on the part of your eyebrows you want to exaggerate.
Good luck on your costume!