Hi everyone.....my working cocker pup is now 8 months old and has mastered the basics, but need to progress onto more advanced training......Seeing I'm new to all this I want to make sure I do things properly, and as these sets can be expensive, I don't want to make a mistake so any advice would be great!!!!!!! Which DVD's are the best....Lisset.....Martin......or Tyers? Thanks in advance!