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.

![enter image description here](https://i.stack.imgur.com/OTscN.jpg)