I've run into this exact same issue several times, and it's currently filed as a bug on our end. Hopefully this will be more predictable/easier in future versions.
That being said, the way I combat this now is to play around with 3 things:
1. Stick length and placement
2. Draggable handle placement
3. Staple placement
So if the bend isn't going the way I want, I'll delete those three and start again, favoring one side more or less. So if I know my character is going to bend his arm one way, I might put the draggable handle closer to the thumb instead of the center of the hand, for example. Or I might leave a little extra elbow room, or change where I staple the arm to the body slightly. Even microscopic adjustments can have a huge impact over the way the character reacts, at least from what I've seen.
If you keep trying this and get stuck, feel free to share your PSD/AI file and we'll try to help out.
I tinkered with my stick placements and got some better control by placing the sticks slightly off centre and more towards the side I want the joint to move to. Thanks for the quick response.
Hey good to know, thanks!