Disciplining a lovebird?

We've had our lovebird for about a month now. He's about 5 months old. At this point, he's comfortable with coming out of the cage himself, shoulder sitting, and crawling all over us basically. Lately however, we've noticed he's gotten a little feisty with his beak. He likes to nibble for the most part, but he's now getting a habit of nipping at our ears or biting at our fingers etc... basically things we don't want him doing. Any suggestions on a good way of teaching him not to do this?