the best way is to get the limbs bending even, and that just takes practice,,you'll get there,,
![Smiley :)](http://www.primitivearcher.com/smf/Smileys/default/smiley.gif)
also consider making the bows longer and wider,,,it will increase your success rate,,, as you gain experience, you can make bows on the edge of breaking,,
![Cheesy :D](http://www.primitivearcher.com/smf/Smileys/default/cheesy.gif)