Feed and exercise him at the same time every day. Be consistent in your expectations of the dog. Always treat him fairly. Make sure everyone in the family does the same. Don't get angry.
Submissive urination is an involuntary response to fear or excitement.
Being calm and ignoring it works much better than yelling. Be calm and reassuring but do not baby the dog. This can cause wetting too. Once the dog has rudimentary control over his bladder, he will benefit from obedience training. Call PAWS for information on locating a training class to suit you and your dog.