In my view, there are 3 key steps for going from backhand grip to forehand grip then returning to backhand grip.
Start by having the disc in both hands in front of you, with the pattern side facing up.
- Flip the disc over in your hands, moving into a forehand grip (don't raise the disc any higher, just have it turn over). Have it sitting in front of your stomach.
- Bring your elbow out wide from your body, ready to throw a forehand.
- Snap the disc back down to your other hand, in front of your stomach, changing to backhand grip as you go.
Snap back to the middle.
Now watch some game footage. Notice how often and how quickly the disc is flipped in the hands of experienced players, as they switch grips. Here's one game to watch.