First things first, your network must be password protected. An unsecured signal leaves you vulnerable to hackers and identity thieves, as well as mooching neighbors who'll slow down your connection. Also make sure that your router firmware is current (you may have to go to the manufacturer's website to find any updates, home routers often don't alert you when new firmware is available).
If your router is up to date and secured and you still need more juice, give these options a try.
1. Location location location— Imagine your wireless signal as waves of sound, where would you put a speaker if you wanted to be able to hear music throughout the house? Remember that your router and modem aren't necessarily a package deal. Often the inconspicuous spot where you hide your modem is the worst one for broadcasting a router signal.
Pick up a longer ethernet cable and find a centrally located, and preferably high spot, like the top of a bookcase or even on the floor of the second story, to transmit. FYI, sometimes mirrors or other large metallic surfaces don't allow wi-fi to penetrate them so, if you're experiencing a room-specific blackout, perhaps the solution is as simple as changing your decor.
2.Change that channel—Have you noticed your signal dipping at peak hours of the day? If you're in an apartment building, it's likely that you're sharing your router's default channel with your neighbors, which can lead to major performance issues. Find out which channels are least popular (and best for you) with inSSIDer, a free program which will give you a comprehensive look at the wi-fi in your area, particularly how many networks are using each channel so you can adjust accordingly. Need help? Check out this great tutorial by HowToGeek.
4.Use a repeater—You can buy a repeater (which will pick up your wireless and re-transmit it so your signal can cover more distance) or you can re-purpose an old router to do the exact same thing. Some routers actually have settings so they can function either in access point or repeater mode.
Otherwise, it's as simple as changing your second router's LAN port to match your primary router. You'll need to alter your IP address slightly, and use the same security settings as on your primary router. This tutorial from LifeHacker will walk you through it, step-by-step.
These didn't work? It may be time to upgrade your router from G to N.