A young Dobie will not need much more than a collar. As your dog ages, however, you will notice its strength increase. For most females dogs this is not a problem, but for the deeper-chested males you may need to purchase a head collar. A head collar is best because it establishes dominance. While using the head collar, you walk right next to your dog's head. The head collar is much like a horse halter. Instead of constantly pulling the collar and being dragged the Gentle Leader, a great brand of head collar, only needs a quick, sharp pull to control the dog.  Most dogs take a while to get used to the head collar, but if you are doing it right it will not hurt them. Make sure you follow all the instructions given to you when you purchase the head collar. Gentle leaders are available at your local pet store. Pinch collars are also effective, but establish a bond based on fear. These should be used as a last resort. Solid training will eliminate any need for a pinch collar. Give your dog a reward when it does something correctly instead of punishing them when they do something wrong. Reward-based training helps your dog create a positive link between the desirable action and getting a reward. The dog then learns what actions go with what cues and carries out the actions in order to earn a reward. This is a humane and highly effective training method.  Dobies have a strong food drive but overfeeding can lead to health and behavior problems. Try toys instead, because food aggression is common with Dobies. When your dog does misbehave, because all dogs misbehave sometimes, try to get to the bottom of the behavior. If you know why the dog is doing bad things, you can possibly alleviate the problem, and thus the bad behavior. If all else fails, get rid of temptation for the dog. Move items it destroys or eats out of its space, so that you are not setting the dog up to fail. Doberman need firm handling. Many people take that instruction as an excuse to be mean to their dog. Firm handling just means that the Doberman is a fairly dominant dog, and needs to be taught right from wrong at an early age. Teach your Doberman that you are its leader when it is a puppy, because being bossed around by a large dog isn't fun.  Dogs can detect and reflect the emotions around them. So if your dog is behaving well, don't go overboard on the reward, because your dog can sense your happiness. When you dog is not behaving well, don't punish your Dobie horribly. It knows you're unhappy. Don't be scarce on discipline. Dobies should respond well to a firm "no". The scold should be directed at him/her, so at the dog and point at them. Dobermans don't respond well to physical punishments, and hitting or physically punishing your dog is animal abuse.  Do not deliberately stare a dog in the eye, especially if they may be aggressive. This is considered hostile, and you may inadvertently be challenging the dog to a fight. The key to training is teaching your dog through repetition. Tell your dog what you want it to do and never give it any mixed signals. This can be harder than you would think, so pay attention to your actions as much as your dogs.
Get an appropriate collar. Focus on reward-based training. Be a strong leader. Practice consistent training.