You don't have to make the pencil in three parts unless you want to.

You could select the faces as groups and assign simple shaders to them in the Hypershade.

Or you could apply a cylindrical UV map to the pencil (edit polys / textures/ cylindrical mapping). From there you take a 'snapshot' of the UVs in the UV editor and export to your paint programme to colour the parts. You then paint in what you want the pencil to look like in your image editor. You can then import the painted map onto a shader (creating a new lambert and choosing to source a file texture for it for example). With a nice simple object like a pencil you should get a fairly uncomplicated UV map which is easy to make initial adjustments to and which might be good practice.

Try Mike's site;

https://www.mtmckinley.net

for a good intro to the hypershade and UV mapping and check out the tutorials here too (time for me to mention the rabbit UV tut again! Joy!).