A seven-month-old puppy has gone past the sensitive socialization period. It is still possible to get him used to new things but it is not as easy as when your dog is young. Plan on spending at least twice as much effort for every little thing.
1. Obedience train your dog. This is vital. If your dog does not sit, lie down, and stay on command 100% of the time you have work to do. If you can not handle this get a trainer.
2. Socialize your dog. You need to expose him to everything, every day. Take him for walks, introduce him to new people, etc. Find out if you have a canine good citizens program in your area (it is sponsored by the AKC).
3. Have your dog neutered.
This is not going to be easy. If you stick with it, however, you will have the best dog ever.