I only wear one with a formal jacket. I pull one corner under my left epaulette, and pin it high on my left shoulder with a plaid brooch. I pin the brooch to the plaid, and pin the plaid to the jacket with a saftey pin; doesn't make as big a hole in my jacket that way. Some fly plaids have a corner with a sewn-in pleat; if yours does, that's the corner to use.