If you're living in the US or any first world country, you probably have wifi. If you're smart, you probably have a password on it. But do you have dead spot around your house? Try these apps and see if you can fix that. The easiest way is to check the channel your router is broadcasting on. That's the specific set of frequencies you are broadcasting on. Why does that matter?
So the WiFi spectrum is pretty large, and you don't use all of it. Each router broadcasts on a certain "channel" or section of the full spectrum. Now when you have multiple routers broadcasting on multiple channels you want to optimize which one your router is on. If less people are using the channel you are on, the better your connection will be. The tools below will scan the spectrum and show you which channel is probably best for you. Now some routers channel hop so they are always on the "best" channel. In most cases, it's alright to leave it that way. But if you have a specific dead spot you want to fix, it might be better to just take one of these tools to that location and see which channel runs best there. Then just leave your router on that channel as long as it doesn't create other dead spots in other areas that you need WiFi.
As always, the placement of your router is also essential. Usually the higher it is and the closer to the center of your home, the better. You can also flash the ROM on your router and use something like DD-WRT but that's a little more advanced for most people. Hopefully the tips I leave here will be enough. But if not, you can always contact me for more help.
Run this on your laptop and it'll chart the WiFi spectrum around you: http://tools.meraki.com/stumbler#q=
A Desktop version of the above: http://www.netstumbler.com/downloads/
Run this on your phone and use your phone to find the best channel: https://play.google.com/store/apps/details?id=com.farproc.wifi.analyzer&hl=en
The tool above doesn't allow you to connect to the WiFi signals above so install this too: https://play.google.com/store/apps/details?id=com.leo.wificonnect&hl=en
For those courageous enough DD-WRT: http://www.dd-wrt.com/site/index