There’s a ton of resources and tips on improving your Wifi Connection. Here’s a consolidated list of links on the must dos for setting up Wifi. I’ve put them down here sequentially, so follow them in this order:
Essential guides for your Wifi router:
For security, make sure you change these 4 settings as recommended by Lifehacker.
Improve your Wifi signal by choosing a free-er Wifi channel for your router.
For the Wifi Ninjas:
If you have the time, go through this comprehensive guide by labnol’s Amit on securing your Wireless Home Network. It also lists tools that can be used to hack Wifi connections.