If you work above the eyes (eyelid), have your model close his/her eyes in a relaxed manner. Children are inclined to shut their eyes tight. Then you can say: keep your eyes closed as if you are sleeping.
Black eye: apply blue Grimas Water Make-up (Pure) to the corner of the eye and some red make up on the sunken areas. Blend the colours into each other. You can tone down the colours with yellow Water Make-up (Pure).
Graze: rub a Grimas Stoppel Sponge over the red Water Make-up (Pure) and smear stripes onto the face.
Hint: if there are multiple scratches in a graze, make sure that they are parallel to each other to create a believable effect.