We have 15 month old male Labrador. He's castrated, if that's relevant. He is very fixated on other dogs (friendliness, not aggression) so we are trying to train him to be neutral. When on lead, he lies down for every single dog he sees and can get quite frustrated. Sometimes he meets the other dog, sometimes he doesn't. We don't actively say no to on lead greetings, but we do try to create distance if we can. He isn't ever off lead aside from private hire dog fields. We take him to the park etc on a long line and again, use treats to praise when he looks at us and we deliberately create distance from other dogs to make this easier. He goes to a very small daycare every other week, only for a few hours, to socialise with other dogs. It's run by a professional dog trainer and the groups are very small (3 or 4 dogs only) and very closely supervised. He is off lead with these dogs, as he's already with the pack so his attention is focused on being with them rather than dodging off.
Anyway, I guess it would be good to get some feedback on whether this is a good approach. The long-term goal is to have him neutral around other dogs but polite when he does interact with them, hence the controlled socialisation at daycare (he has this second bit nailed pretty much).
Also, we were invited earlier to have him off lead to play with a dog we met in the park. He was on his long line so I let him off. It was a really positive experience, but I'm now a bit worried that we've undermined our 'neutral' approach!