3D Camera Tracking Nightmares

At this moment in time I'm learning the art of 3D camera tracking using Autodesk MatchMover (it's free with Maya) and finding it to be a fairly straight forward yet frustrating process.  The part of the process I'm having issues with is setting up the Coordinates so the grid is aligned with the ground in the video footage.  At the moment I have been getting by with trial and error but still haven't grasped what I am doing right or wrong. 

This is a camera track attempt I did today:

Most of time went into getting the coordinates right. I have seen some tutorials where they seem to have the experience of placing the trackers in the best place's and setup the coordinates with ease.  I have a feeling it's very simple to do but I just can't get my head around it. I will not give up! 

The zombie and animation can be downloaded for free from http://www.mixamo.com/ and you can follow them on twitter too.  The BG footage is from gettyimages.