Unfortunately, some folks just have no common sense when it comes to owning a dog -- I have been in the OP's shoes helping a dog that found itself on the street -- GoodysgotaCuda makes a good point that it takes repetition to train the basic commands - sit, stay, down, come -- let alone more complex commands for hunting dogs - "Back", "Over", "Dead bird" etc. I have trained dogs for over 35 years
(we currently have 4 Oakley English Setters - Dram, Radar, Shade, Taser; plus my American water spaniel, Ruger, who is my duck/goose dog, and my wife's Newfoundland, Beignet, who is a trained water rescue dog -- all wear collars with ID tags that have our address, home and cell numbers, and all are chipped. We have kennel runs both at home and the farm, plus fenced in areas for them to run. Plus crates inside for them to sleep in on cold nights) Responsible dog ownership is like responsible gun ownership -- you have to learn it and constantly train it. We have never "lost" a dog (i.e had one that ran away) primarily because we put a lot of time and effort into training and caring for them -- this is because they are like family members to us and we love them very much and considering what a good ES, AWS or Newf costs these days, it wouldn't make much sense to buy a dog and not train it, then lose it to a mishap. Lost dogs are kind of like accidental discharges -- they should not happen.
We use British-style slip-leads -- a leash that has a loop for your hand and a loop with a sliding ring that goes over the dog's head -- very simple to use and very effective for walking and training a dog. Academy often carries them and you can order them from mendotaproducts.com --