These are the 6 important tools for a young puppy
A harness is what I use mostly for young puppies because it allows a puppy to pull. Puppies have no concept of not pulling and walking nice on a leash usually. This also prevents them from choking themselves out with a flat buckle collar. The strongest part of a dogs body is the chest. By using a harness we also prevent unnecessary stress on our young puppies.
4 or 6ft leash
I usually have one of these. It is usually light weighted so the dog can drag it with no problem. The only issue you will face with this leash is that a puppy doesn't understand leash pressure and how to give in. You will notice this when you pull a puppy forward and they resist by pulling in the opposite direction. This is also known as an oppositional reflex. Eventually as the puppy gets older we teach them how to give in to pressure. A little stress is not a bad thing for our dog but we have to set them up for success.
flat buckle collar
These are your regular flat collars most dogs have. I like to keep this in my arsenal but i prefer a harness more. Again, puppies can choke themselves with these collars when they are young. I still condition them to this collar because we will be using it a lot later on. As your dog gets bigger, a harness reinforces your dog pulling. This is when i prefer a flat collar. It gives us more control of the dog's head. If we can control their head then we can control what we want them to look at and not look at.
This is my favorite tool for young pups. Its like having a regular leash and a long line in one. You can let the dog go 20ft away from you or stay right next to you. A puppy natural instinct is to follow the group or leader. If your puppy is 20 ft away you will notice that he/she might naturally run to catch with you so they are not too far away from you. What I also like about the flexilead is that you still have control of your dog just in case your puppy sees a leaf or paper or some other object they want to chase across the street. You can immediately change the leash from a long line to a 4 or 6 ft leash.
A crate has been called many things( a den, the dog's safehaven, etc). A crate, to me, is a simple management tool. If the dog is in its crate he/she can not get into trouble( chewing on shoes, soiling everywhere, biting on furniture). Puppies sleep in crates and spend time in it when we leave the home. I would suggest that you don't get your dog a crate the size of a mini mansion. They only need to be able to stand up, turn around, and lay down.
An xpen is a great tool. Its like a crate but bigger. You can put your puppy in it and throw in some chew toys. This prevents boredom and it allows your puppy to feel included in the family. This will prevent running around the house yet will give your puppy enough space to have fun.