1: Start by priming your centipede black or brown, or prime it white and then paint a base coat of dark or medium brown over the whole figure. The diagram represents each segment of your centipede. Do each step to all the segments before proceeding to the next step. The unnumbered step in the diagram represents the belly portion of each segment; it uses the same general technique, but with lighter colors.
3. Now choose a lighter tan and do the same thing as in step 2, painting thin strokes over those you've already painted. These strokes should be shorter than the previous strokes. Do the same with either a darker brown or even black at front of the segment, keeping those strokes within the brown swatch painted in step 2.
4. At the back of the segment, repeat step 3 with even lighter-colored and shorter strokes. At the front, paint a black line to separate this segment from the next. You can do this with brush and paint, or with a little black ink wash.
5. Finally, do a fine light -- almost white -- line across the back of the segment. It can be a straight line, or a line of closely packed dots (to help blend in with all the previous strokes.)
That's it! You can use the same technique for the belly segments using lighter colors (or any palette you prefer), as well as for the legs and antennae -- just use longer and thinner strokes. Paint the eyes your preferred color, and that should finish off your centipede. I like a gloss varnish on this figure to give that exoskeleton some sheen.
You can also use this basic technique to paint your roaches. Simple paint each roach as if it's one segment.