victorcharlie has done some of this. Gotta agree with most of what he say's but, it your talking about a bird dog, I like to let them grow up befor training starts, 12 to 18 mos. Most trainer's disagree with me on that but I like the dog to get out that puppy foolishness befor we start. As for leash training, it's fairly simple. It's called a check cord and for a puppy require's no collar. If your pup already has one, fine. Get a length of light clothes line and tie it to the collar, depending on the size of the pup, up to about 4'. Let the pup drag it all the time and learn to deal with all the little snags it'll produce. Step on it from time to time and now and again AFTER YOU HAVE THE CHECK CORD IN HAND, call him and haul him in, even if screaming and fighting. Never let your dog tell you "NO". He'll get used to the cord and will learn to give to it's tug's.
As your pup grow's, increase the length of the cord up 20' or 25'. Never let him go without it. Do not tie a not in the trailing end when the pup's running loose.