Here is a list of Training Tips: (Check back as More will be added)
Training Tips Marking by Pat Burns.pdf
As this is a spoof on handling, it does show you what so many of us do at the line, when we are nervous, etc. Please watch the dog closely, because it shows you how we as handlers can throw off our dogs, based on our movements. Do you see how the dog ducks, moves to the left, or right, etc. In some cases moves the direction of the line. Watch: https://www.facebook.com/cripplecreekretrieverstx/videos/591217503748145/