Notice the reflection
Look at what the mirror will reflect from your usual viewing position. A window, a plant or a quiet part of the room can provide a useful focal point. Avoid positions that send strong reflected sunlight into an uncomfortable area.
Measure the whole piece
Check the external dimensions including the frame, the weight and the hanging method. The glass area and overall dimensions may be different. Make sure there is room for the fixing and any necessary clearance.
Choose the right installation
A wall mirror needs a fixing appropriate for its weight and wall type. A leaning mirror may require an anti-tip arrangement even if it looks stable. Follow the instructions supplied with the specific item.
Protect the finish
Use a soft suitable cloth and avoid soaking frame edges or backing. Apply a permitted cleaner to the cloth rather than spraying into joints. Check the care guidance for metal, wood or painted frames.