I agree, a dremel works well. You can buy a nice little kit, quite cheaply with lots of cutting heads. Then experiment with different heads to see which works well. I use dremel on stone to carve offerings for sacred places for when I visit. Slate works particularly well. You shouldn't cut yourself if you are careful. For small stones I would say buy a clamp to keep your fingers away from the cutting. You can paint into the cuts to add definition or leave it natural. I also use a stone polisher, although this is a long term project as it takes about 6 months! Polish first then cut the rune.