This is the wrong way:

This is the right way:

Why? 

It seems natural to hold the paddle as if it is a scoop. However the whole idea behind the angled blade of a bent shaft paddle is efficiency. Holding it correctly keeps the blade vertical in the water for most of the paddle stroke. A vertical blade means the force you put against the water will pull the canoe forward. A blade that is not vertical in the water will be pushing the water up or down, not back. 

In the first picture, the blade looks vertical. But as Sarah goes through her stroke, the blade will be pushing the water upward, not back.

In the second picture there is a more positive angle on the blade at first but as the paddle reaches her hip through the stroke it will be vertical. The picture below is from Grey Owl Paddles and shows this concept: