The best place to put your new reed diffuser is in a high traffic area. It works well by interior doorways, in hallways, bathrooms or any other transitional area in your home where you will notice the change in scent as you move from one area to the next. It will disperse the scent best when it is in a warm area of the room with good air circulation.
Make sure the air is circulating into the room, via a vent that is pushing air into the room. Make sure it is not flowing out of the room, for instance by a open window or cold air return. These places can deplete the diffuser quicker and lessen the fragrance because the scent is getting sucked or blown out of the room.