By Ocean In Space
Using a Mirror Ruler in your drawing program, sketch a rough outline for your illustration
Turn off your Mirror Ruler, and on a new layer, sketch out a more detailed version
On a new layer, use a steady hand to make a final 'ink' of your illustration
Make a new layer under your 'ink'. Fill in your illustration with flat colours
Add highlights and shadows to create more dimension
Add in your final touches like a background, and you're done!