Is there an obedience class near you taught by a qualified trainer? You might try contacting your local kennel club or poodle club for a reference. I don't recommend the training provided through the chain stores like Petsmart or Petco. In my experience it has been very low quality.
I like to use a pinch collar on my young poodles. I find that I can get by with a very light correction with these collars and that my dogs learn what I call "self-carriage". That is that they learn to walk on a loose lead without always leaning on the leash and collar. Usually around age 1 yr I transition to a typical buckle collar with great results.
I never use halties, martigales, harnesses etc. I feel like a dog never learns to walk on a normal leash and collar.
26lbs at 6 months is very light. How tall is this boy? He has been treated for worms, right? I like to feed a high quality food where the first ingredient is a high value protein source. So chicken as an ingredient is better than chicken meal which is better than poultry meal etc. Most grocery store dog food is junk but the Costco brand of food is good quality and not too expensive.