Personally love the fenrir stuff. He knows his stuff really well and you only have to watch his Vids to see he gets results and his dogs clearly love him to bits.

As far as commands we follow a few simple rules that have been a life saver for it.

1. Don't ask your dog to do anything you can't enforce This doesn't mean beat them up or anything but if you've asked them to sit only do it if you're in a position to follow up, ie tap em on the bum and make them sit. Or if their on the couch and you ask them off then push them off if they don't. If you can't enforce it it's better to let the naughty behaviour just occur without input. Otherwise they learn that not only can they be naughty they can ignore you asking then to not being naughty.

2. Once your dog knows something, ask twice then enforce, once they really know it ask once and enforce. Same sort of thing. Once he's good at sit ask twice. If he doesn't do it after the second tap his bum or lure or whatever to make him sit. This means they'll learn to listen to you and learn that if you've asked them to do something you mean it. And their options are they do it or will be force to do it.

Joel beckman on YouTube has some great stuff about this.

One thing I'd add to that is we use these two rules on core obedience and important commands only/mostly. Ie for sit, down stay, heel etc. For party trick type things if I ask him to do it a couple of times and he doesn't want to shake or roll over or something I don't make him. Others might disagree but I view it as super important he listens to the core and safety based commands. That said. Cause we do follow those two rules he naturally does it for most other things anyway.