Lots of sound advice here. I have found through raising several dogs from puppyhood:
I MUST be seen as the "alpha dog" by my dog.
Positive reinforcement ALWAYS works better than negative reinforcement.
It's true that it's hard to "teach old dogs new tricks". Puppies and adolescent dogs are much easier to train than trying to change an unwanted behavior later.
Crating as a puppy is a good thing, not punishment. I didn't crate my first dog as a puppy and he always had at least some separation anxiety throughout his life (which led to many unpleasant surprises when returning home). I crated my last 2 dogs as puppies and it turns out they ended up loving their crate -- it was their "safe place" and it was the "go to" spot for one of them during thunderstorms.
I had a good friend growing up who had a beagle mix live to be 22 years old!
