Prevent black colored pencil from blending into adjacent colors I'm new to drawing with colored pencils. I've drawn a bear that has a nose and mouth in black, but I can't quite figure out how or when to draw these black parts without accidentally grabbing some of the black color when filling in adjacent colors. I've tried doing the black at the end after the rest of the colors, but it doesn't seem to be as crisp compared to when I put the black down first. 

It might be hard to tell in the attached drawing, but the black from the nose and the line down to the mouth, as well as the dots on the chest, sort of got blended into the light tan/brown color, even though I tried to be super careful to avoid the black. My pencils are very sharp so I don't think that's the issue. I'm wondering if this is something that just comes with practice? Or can someone recommend a method or technique to applying crisp black lines to colored pencil drawings that prevents them from accidentally blending into the colors next to it. Btw, in case it makes a difference, I'm just using cheap Crayola pencils.
Lots of good advice here, but you may also want to consider using a fixative to preserve the drawing as you work it. Fixative, found in convenient to use spray cans although you can get it in liquid form, chemically bonds and protects the pigments applied to the paper. It is nearly a requirement when working in pastels and I regularly use it to protect my graphite pencil drawings. Look for workable spray fix in this case.

So you would draw the dark details, spray fix them, then work the light areas and there will be no smudges. The reverse is possible as well but sometimes the fix will darken light colors. 

Fix is toxic so spray outside or have good ventilation.