To get the best signal, the ideal place will be near a window. Try a few different areas until you find the one with the best signal.
Concrete or wooden walls can weaken the transmission of wireless signal.
Electrical appliances that project strong electric or magnetic fields such as microwave ovens, refrigerators and satellite antennas can negatively affect your signal. Place your router away from such appliances.
Note: This Q&A question only applies to devices with a SIM card slot.