Before addressing any other training, housebreaking is always the first concern.
So much more than just "sit", "stay". A well trained dog is a respected member of the family; and not just the family dog.
Behavior modification is the changing of unwanted behavior through conditioning.
Training removes the obstacles that stand in the way of a rewarding relationship with your dog
WHAT ARE WE REINFORCING?
There is a new wave of new trainers who use "Positive Reinforcement". However, there is definitely a wave of confusion about what this means and how it applies to the dog being trained. Let me clear this up. If the dog is doing something good, or if the dog stops doing the unwanted or negative behavior, THEN the dog should receive "Positive Reinforcement" by way of praise, hugs, belly rubs, treats, a toy; whatever the dog will perceive as a reward for good behavior.
Here's the confusion part. If a dog is jumping, biting, and out of control, and a trainer or family member offers the dog a biscuit to distract the dog; yes, he might stop the jumping, biting and barking but it is TEMPORARY and SHORT LIVED and most importantly you are REWARDING THE DOG FOR BAD BEHAVIOR; thereby teaching / conditioning the dog that he will be rewarded for jumping, biting and barking and whatever else is on the agenda.
In short, the dog is receiving "POSITIVE REINFORCEMENT FOR NEGATIVE BEHAVIOR".