CORRECTION: During this video I say GPS operates on 900mhz, which is not correct. According to Wikipedia (http://en.wikipedia.org/wiki/GPS#Satellite_frequencies) GPS operates on 1.57542 GHz (L1 signal) and 1.2276 GHz (L2 signal). I apologize for the error.
Here are a few tips when mounting your APM to your RC craft.
This is a part of a complete how-to APM series that I'm putting together on MyGeekShow: http://www.mygeekshow.com/beginnertoexpert/topics/AutoPilot.html.