One thing to bare in mind when using photography is that if you decide to trace you photographic reference you will have to make sure that whatever you are incorporating into the image , it will have to be drawn to match the existing perspective or camera angle or you will end up with an unconvincing drawing.
Often you will find the best way is to use photography as a reference point only and reproduce it to your own layout. You will find this less restrictive.
If you are using a Fabre-Castell pit artist pen, brush nib, use only light pressure (I used hardly any at all),and drag the nib across the surface of the paper. This will give you a nice line that will suit the craggy stonework and gargoyle very well. I avoided going for a consistent smooth line as I felt it would not suit the nature of the drawing, rendering it too technical and precise. If you apply too much pressure to the nib you will end up with thicker line work an may look clumsy. Draw a few practice lines first to test control over pen strokes. The less pressure the finer the line, the more pressure , the heavier the line.
Notice on the short clips below how the pen flows across the paper.
The inking is being applied to a blue line print on coloured paper
here is a nice clip by Carly Lyn using exactly the same pen. This clip is obviously shot with a higher spec camera.