A harness is a good alternative to a collar because it eliminates pressure from the dogs neck, preventing possible neck injury.
Allow the dog to wear the harness around the house for short time so that he can get use to it. Make sure you praise the dog and give it treats.
Be sure it is snug enough so that he can't slip out of it. Correct fitting means you can fit two fingers between the dog and the harness. You don't want the harness to be rubbing be sure it fits properly. Only use the harness for taking the dog for a walk and take it off when you come back from the walk. Do not use the harness for running or hiking. Be sure that it is a comfortable fit for your dog.
Do not take the collar off because the identification tags are on it and they are very important.
Check out this video on how to properly measure your dog for a harness.
Professional Pet Sitting Services offered in the Upper to Mid-Pinellas County Area