Assuming you dog has a hunting background/good drive, you couldn't go wrong doing the training yourself. I trained my current dog with me hunting in mind, not hunt tests. From personal experience, when duck hunting, the majority of your birds will be somewhat easy marks for the dog. Repetitive marking and denials helped really turn it on for my dog. Essentially, if you can train your dog to be obiedent, sit still and be quiet, the natural instincts will do the rest.

That's just my .02, for what it's worth.