I was introduced to scratch-art in high school and have loved it ever since. The problem I repeatedly encounter is in keeping the surface of the paper unmarked where I want it to remain black. I have tried a number of solutions as far as a storage is concerned, like keeping it between two pieces of paper and even buying a folder carrier for my projects to keep them protected. I don't wear jewellery when I work and that helps a lot.
I find though, that my faint pencil sketch I do before starting often shows up and is difficult to erase. the pencil is very shiny and reflects a lot more light than the paper does. The eraser makes more ugly marks than the pencil does. Further, I haven't figured out what to do if I do make a mistake.
Does anyone have tips for preventing ugly marks on scratchboard paper or fixing them once they've occurred?
Is there a suggested medium to sketch with on this sort of paper to lay out the outline of a design?