I have purchased a Netgear N300 with the hopes to improve the wifi signal in my house. I now however need a modem/adsl filter for our internet because our connection is through the phone line. I would have returned the purchase for a combo package but unfortunately I left it too long to install it.
Try using a network analyzer and have a look at which channels are unused in your area. Or you can just go through all 12 of them manually and see on which channel you get the best signal quality.