Set a Black Point via Curves
Unless purposely going for a muted look, you should make sure your black artwork is actually black. Sometimes, you may open art that isn't quite that blackest black. To do this, go into your layers panel and select a new adjustment layer for curves. Once you have that open above the layers, you will see 3 eye droppers on the left side. Select the top one. This gives you an eye dropper. Now sample anywhere in the artwork that is supposed to be pure black. And the adjustment is automatically made. It will be made on the layer above. You can click the eye icon off and on to see the difference with and without the black point.