The key to being comfortable with the bo is just getting your body used to it. One note is that you need to make sure you have a balanced bo. I've used bo that have curved and I notice a world of difference in how unwieldy they can be. Here is a good exercise that even after a few years of kobudo I do regularly:
*Start standing naturally with the bo horizontal at an arms length from your body. Your left hand should be grasping the weapon palm down, the right hand should be palm up. (this grip is called jun nigiri http://tinyurl.com/gr3mm
*Open your hands so you have an open palm grip (called Hasami Nigiri)
*Slide your hands together so that they meet at the center of your bo. The bo should be vertical and your hands will be together and look like youre about dive into a swimming pool.
*Continue sliding your hands past the meeting point until the bo is horizontal again has flipped 180° Now your grip has switched (your left hand was palm down, now it is palm up)
Do this movement over and over. I've probably done this many thousand times over the years. The bo should basically flip 180° back and forth as you do this exercise. The goal is to get faster and faster while at the same time learning how tightly to grip the bo. There shouldn't be any jerky or sticking movements, if there are you are holding too tight. Eventually you will get a great feeling for the bo's center of mass and you'll easily notice if one hand is accelerating or moving too quickly.
After you're good at that, add a strike. Flip the bo and do an overhead strike. For the strike, chamber at your hip and not under your armpit or on the outside of your arm. This allows for fastest transition. Flip the bo again and do an identical overhead strike with the opposite hand out.
... After you're good at that, practice stepping out into zenkutsu dachi with every strike. Come back to musubi dachi as you transition sides with the bo and step out with the same side foot as your striking hand.
...... After youre good at that... just kidding =) but it really can go on and on and on with variations of this drill. The main goal is getting a fluid feel of the weapon. Once your strikes are fluid, pay attention to the path of the bo's tip and try to strike along the same path every time over and over. Then work on speed and snapping the tip by twisting your wrist at the last moment (start the strike with your hand holding the bo as if you were talking on the telephone and at the end of the strike twist your wrist so the palm side of your fist is pointing directly away from you.
sorry if this is too basic, or hard to comprehend. lol this kind of stuff is hard to communicate without pictures (theyre worth a thousand something or others)