Well, you don’t need a PhD to do this well, but it sure is easy to cause problems with Wifi. “Apple”:http://manuals.info.apple.com/en/Designing_AirPort_Networks_10.5-Windows.pdf has a good guide to the obvious pitfalls.
The most important is that if you want several access points to work properly, you have to put them all on the same frequency and give them the same SSID, the laptops and things are supposed to be smart enough to “roam” from one AP to another. In practice, I’ve had plenty of problems with this. For instance in Seatac near Gates D-9, AT&T has about 10 access points all with the same SSID but different channels, so getting a connection is very strange inconsistent. I had another buddy who had three APs in range, all with the same SSID but on different channels and one AP was actually dead, it didn’t have a network connection, so depending on where you started, you’d lose internet connectivity. That’s a long way of saying that it is far from perfect.
There were lots of posts about this in 2006, so we’ll have to test to see if issues like from “then”:http://www.smallbusinesscomputing.com/webmaster/article.php/3600486 still exist. One thing that makes it easier, is that if you do put access points on separate frequencies and separate SSIDs, most modern laptops, will roam from the client side connecting and reconnecting as needed, but what you really want is for the client to look at two signals and automatically flip when one becomes stronger.