Portrait Step by Step

I have wanted to paint a portrait of my Grandmother who passed away in 2011 for a few years now... I have finally located a photo of her that approximated what I wanted... Her final years she was feeble and bedridden. I wanted a photo of her when she was still active and strong, as I recall her.
This is my first step - converting the photo to a line sketch on a stretched canvas. You can see I used a grid layout to ensure the sketch is accurate to the original photo