This tutorial works for both digital and traditional, mostly on the digital side.
Tools you can use are pen tools or the tablet for the lineart and the hard brush or the paint bucket for colors.
Downloadable pencil brushes: Real Pencil Brushes for GIMP
(GIMP) Paint Tool SAI Pencil Brushes
(SAI) Best Pencil Brush set
Website for Sonic References: Sonic Art Archive
Sonika the Hedgehog © *Sonikku0691
SONIC RIDERS © SEGA/SONICTEAM