How can I get my Wii to get a better wi-fi signal?

I just got a wireless router for my internet so that I could play Monster Hunter Tri Online. I set it all up and was able to get online but about an hour later my Wii said it lost the wi-fi signal and disconnected. I have moved it so that it is higher up on a wooden bookshelf (It is sorrounded by books which might block the signal but only a little). It is not to close to any metal, and my Wii is under the wireless router and a little in front of it. There is a cordless phone near the router which I heard may mess with the signal but there is a bookshelf between the router and it. Is there any way I could increase my connection or change its location to get a better signal? Any help would be great thanks.