I'm definitely not an expert in dog training but I have a maltichon that is a puller. She would pull so hard on her harness she would choke herself and cough. One of the staff at a local dog boutique recommended the Easy Walk Harness and I've have had great results using it. Chloe doesn't pull anymore when I take her out.
Here is a link.
Easy Walk Harness, No-Pull Dog Harness - Dog Training Supply