9. Centralize the Router’s Signal
Routers are actually omni-directional transceivers that transfer information data between your modem and connected devices. This means that there is essentially a bubble of signal connectivity surrounding your router. But, if there are walls or furniture crowded into that bubble’s space, it can interfere and degrade the signal strength. Generally you should avoid placing your router right next to an exterior wall because it could end up chopping its output by 50 percent since half of the connectivity bubble will exist outside your home. This can lead to slower internet and transfer rates. Try to keep your router in a centralized location free from obstructions to ensure all your devices are receiving a strong signal.
http://www.linksys.com/ca/support-article?articleNum=140545 Via LinkSys.com
8. Keep Your Router Away From Other Appliances
Microwaves, cordless phones, and even florescent lights can all interfere with your Wi-Fi signal. To diminish the conflict, try to ensure your router isn’t too close to household appliances. Signal interference can also be caused by neighboring routers. So if you notice you’re continually getting a weak signal, it could be because some else’s router nearby is set to the same channel.
http://www.howtogeek.com/126327/how-to-get-a-better-wireless-signal-and-reduce-wireless-network-interference/ Via howtogeek.com
7. Change the Channel
Nearly all wireless routers transmit at the 2.4GHz wavelength and work within the set boundary of the 802.11 standard. But since quite a lot of other devices, such as microwaves, cordless phones, and bluetooth gadgets, also operate on the 2.4GHz band, problems invariably arise with everything vying for a spot on a finite amount of spectrum. The result usually ends up being significantly reduced bandwidth on any single device. To solve this problem of competing devices, the 2.4GHz band is divided into 13 separate channels. However, much like a semi-tuned radio, those channels can sometimes interfere with neighbouring frequencies. In order to prevent this, you should set your router channel to 1, 6, or 11 (1, 5, 9, or 13 for residence outside the US). And to further optimize coverage, you can also talk to your neighbours and make sure your routers are set to different channels.
http://www.howtogeek.com/howto/21132/change-your-wi-fi-router-channel-to-optimize-your-wireless-signal/ Via HowToGeek.com