Be vigilant and watch for when he is close and might bite. Calmly say no biting. Make eye contact. Lots of kids go through this phase and it's best to watch carefully all the time. It is a pain, but it isn't appropriate to get angry or punish, especially at this age. They are learning about things and do not realize it hurts. This approach worked for a friend whose child did this at about the same age.
This is a stage...but the no bite did not work for me........so I would take her finger and gently bite a lil bit and showed her how it hurt and she stopped real quick. I did this because one day her and a cousin were playing and she bit her cousin and took a huge chunk out of her skin.and I actually talked to her doc and said gently biting them back is not wrong.