Start near the centre.
Place the router in an open, reasonably central spot where it can reach the rooms you use most. A shelf or desk is usually a better starting point than the floor or a closed cabinet.
Give the signal some space.
Thick walls, metal surfaces and large appliances can obstruct wireless signals. Keep your router clear of them where practical, and avoid enclosing it in furniture.
Match the connection to the job.
Where your router supports both bands, 5 GHz can be useful closer to the router, while 2.4 GHz may reach farther. A wired Ethernet connection can be useful for a fixed desk or television. Actual results depend on your equipment and surroundings.
Check room by room.
Try the same device in different rooms. If performance is good near the router but weak farther away, the issue may be Wi-Fi coverage rather than the internet package. Discuss mesh or access-point options with a technician if needed.