I started using blending stumps and then I came across some 6" wooden stick cotton swab applicators that I really like. They come two to a package, so you can use a new stick with each color range and avoid cross-contamination. The longer applicator also gives you more range of motion and freedom in coloring, I think.
Here are some of the latest images I practiced on this weekend. If you haven't tried this colored pencil technique, I'd highly recommend you check it out. The results are quite astonishing. It does take some investment on the front-end, but the dividends are very satisfying.
The stamps used: owl (Inkadinkado), butterfly (Autumn Leaves), bunnies (a RAK from AMKs_Mom), heart (Marah Johnson), poppy (Rhonna Farrar).