Adobe Illustrator and Scanned Drawing.

Simple drawing with sharpie of Pekingese.
Step 1 Scan
Step 2 Place in Adobe Illustrator
Step 3 Lock Layer
Step 4 Make new layer and lock down for each  part of drawing you manipulate
Step 5 Use Pen tool- Paint brush tool Curve tool,  Shape tool, Copy layers  and Options-Transform- Reflect when ever possible.

Starting Out

Pen or Brush Tool