Breaking In a New Dog

We've been very spoiled over the years... have always adopted shelter or rescue animals, and have always gotten well behaved pets.... until now.

We got our "new" dog (now 4 weeks) - a 2 year old (+/-), 15 lb poodle or poodle mix from a shelter. We already have a 7 year old Standard Poodle.

He jumps (boy, can he jump!) and mouths us constantly. He knows "sit", but only does so when he wants to. He pulls badly on walks.

We've never been trained (neither have our dogs). The internet seems to be a jungle of misinformation and opinion.

After seeing Brian Kilcommons do an in-store to promote the "Good Dogs" book probably 10-15 years ago, I respect what he has to say.

Should we get a trainer, watch DVD's, go to a training class at a local Petsmart, etc.

What about collars that are supposed to stop pulling... Gentle Leader harness was recommended by the Petsmart, but I don't know who to trust.

We're frustrated and know it's up to us to help the dog learn, but don't know how.

First steps, please!!

Scott