Expect adolescence! All children and dogs go through it, but with dogs it’s usually months instead of years.  This is the worst chewing stage of your dog’s life!  Go back to confining your dog to a safe crate or room when you can’t supervise closely.  Spaying and neutering prevent many problems but there will still be more independence and other problems from 6 months of age until 1 ½ to 2 or 3 years of age. Unneutered dogs can be adolescent until 4 or 5 yrs of age.  Don’t give up on your dog when he becomes adolescent; they all go through it.

Continue confinement whenever you are not watching your dog; this is the worst chewing stage of your dog's life.  Giving an adolescent more freedom than you would give to a puppy in housetraining leads to serious problem behavior.

An adolescent dog needs to relieve himself outdoors 4 to 6 times a day for five minutes and play or walk with the owner 20 to 30 minutes twice a day; an adult dog once a day.

Roughhousing, wrestling and tug of war are what the police do to increase aggressiveness, therefore counter productive if you don't want an aggressive dog. Tease and trade a favorite toy or treat for the retrieved toy or stolen object  your puppy has in his mouth.  This enables adults and children to play with the puppy without taking things from the puppy and causing aggressiveness.

At home at the door, until you have one word verbal control over your aggressive or timid dog, put him somewhere else when you are expecting guests and bring him out pleasantly with treats after your guests are seated.  Have some treats available to your guests to give or toss to your dog.  Never allow anyone to approach or make eye contact with a dog who is timid or suspicious. Even if your dog is friendly, it’s always better for your dog to be called to the person for petting or treats, rather than for the person to be allowed to approach the dog.