Standard procedure for bow drill is to carve a nice flat hearth board - a rectangular plank of wood that you cut a notch into to collect the ember.
The thing is, I really hate cutting that notch! It's a tedious and sometimes slow process if the wood is dense.
Today I tried drilling directly into the 'crook' of a branch - the elbow where the branch forks. That way the ember already has a place to collect (in the gap between the 2 branches).
It didn't work for me this time as the drill kept slipping, and then when I did get it stable I drilled all the way through the branch which was a bit soft and rotting.
I'll definitely keep at it, though I feel getting just the right stick with just the right crook in it is going to be key!