I found a penciling tip on www.learnpysanky.com:
"Oksana recommends using a non-repro blue pencil, available at most art shops (and many business supply stores). It stays on well without smudging, and comes off easily in the final stages of cleaning off the wax."
I started with using #3 the Staedtler Non-Photo Blue pencil and recommend having a good pencil sharpener on hand. It does not smudge and is erasable with a white eraser. However I prefer, The Pentel Blue 0.5 is the better lead, longer lasting, harder (rarely breaks) and best of all it's 0.5 my preferred size. The shade of blue is darker than the standard non-repro blue so it requires a lighter touch.
The Pilot Color ENO Soft Blue 0.7 is the perfect shade of blue, but it is much softer (it easily and often breaks) and only comes in a 0.7 size.
So the choice is yours - 0.7 / softer but great colour, or 0.5 / harder and a little dark.