Help me with my site survey please!

I need some help doing a site survey for my new 5 lnb dish. I purchased the HD DVR and a slimline dish 2 weeks ago and want to get everything prepped right for the install. (which may or may not be soon since I have not seen any equipment yet and no one called within 3 days to schedule an install like the said. They did charge my credit card immediately though.) My current 3 lnb dish has a 40% siglnal at 119 when there are no leaves on the trees and no signal when there are leaves. I need to very accurately determine which branches need to be trimmed on my neighbors tree across the street (if I can get permission) and/or relocate to a spot that is totally in the clear or greatly minimizes what needs to be trimmed. I have a Suunto compass/inclinometer but am not 100% confident where I need clearance from for each satellite. I came up with some locations at a website that gave azimuth and elevation but I forgot to bookmark it and now am unsure whether the listing was magnetic or true north. Could you guys please point me in the right direction with some tips and links. I do not want the installer to show up and say I cut the wrong branches or that the location I thought was clear really isn't. I want to be 100% sure things will go smoothly. Thanks.