I would suggest making sure that it is eating well before even thinking of handling. Once you are ready for handling start with short sessions about 5-10 minutes near it's cage. I usually try to handle at night, when they are more alert. Pay attention to their cues. If it stops eating, ease up on the handling sessions. Some bps are just more shy than others, and others are just grouchy. You'll have to figure out where your bp's personality lays, and work from there.

There are also lots of other threads, with tons more advice. If you would like to read some more, just try using the search function. Good luck with bp.