Looking at any drawing in the reverse whether you take the main lines like I do or look at your sketch in a mirror, or even turn it upside down; it gives you a different perspective of the image and allows you to see anything that looks out of place quite quickly.
The added advantage is that all my final lines are darkened and ready to transfer to my drawing paper; without my having to do it a second time or darken the back of my outline drawing.
I have found that "scribbling" over the back of the drawing with a softer pencil and then transferring the drawing often leaves a lot of loose graphite on the good paper which can be smeared and create a mess.
As you can see each dog was drawn on a separate piece of paper. It is here that I decide where the best position is to have the dogs overlapping each other to create interest instead of having them separated with a space between them. The two drawings are taped together so they don't move.
Then two small pieces of low tack tape is used to hold the drawing in place on the acid free paper while the outline is transferred to down. That way the image doesn't shift which is time consuming to correct and often causes damage to the fine paper.
