Set down that tequila sunrise and boogie. Ask guests to dress in costume and bring some of their favorite disco music. Set aside some space for, or rent, a dance floor.
Dancing is key to a good disco party.
Hang a mirrored ball from the ceiling in the center of the room, above the dance floor. Position spotlights in the corners of the room so that they hit the mirrored ball at strategic angles. Keep the dance floor well lit, but leave the rest of the party room relatively dim, occasionally breaking the darkness with lava lamps. Have some beanbags on the floor for cozy conversations. When your guests arrive, greet them with a jive handshake and direct them toward refreshments and the dance floor.