I use for first leash training in my fenced back yard a flat collar that just snaps they are usually a small size size puppy necks are even smaller than my cats lol! and I use a regular leash 6-8 foot length. Then as they get a bit more trained and are ready for unfenced areas they graduate to a no-slip collar that I buy at petsmart. and continue using a 6-8 foot leash. The non-slip collar is very important to use in a wide open nonfenced area because with regular collard they can slip out due to the size of the neck being bigger than their head! when out in the fields/beach running I use a 20foot leash with them. I only use retractable when im traveling with them. I also use choke collars but that is because they need to get used to them for show training, and actually I dont think my dogs notice the difference between the 2 because they seldom pull once leashed.