first off harness wont do anything to help the nipping and i personaly beleave it only makes pulling wors.
for the nipping sit with him and soem treats, touch his collar give him a treat do this as many times as it takes but he will relize with in a couple of times that if he lets you ge gets a treat.
start with just a tap, one he is letting you tap/touch his collar, work on keeping your hand they for a couple of seconds longer. till you can hold it. again give treats when he does well.
then get the lead, dont clip it, just hold it and again tap the collar and treat. do the same as above then try clipping and un clipping using the same tequnec.
it will get the the point that he will push his head to you wanting you to touch his collar.
this works for feet, tale, ears, teeth eyes etc
for the nipping sit with him and soem treats, touch his collar give him a treat do this as many times as it takes but he will relize with in a couple of times that if he lets you ge gets a treat.
start with just a tap, one he is letting you tap/touch his collar, work on keeping your hand they for a couple of seconds longer. till you can hold it. again give treats when he does well.
then get the lead, dont clip it, just hold it and again tap the collar and treat. do the same as above then try clipping and un clipping using the same tequnec.
it will get the the point that he will push his head to you wanting you to touch his collar.
this works for feet, tale, ears, teeth eyes etc