Here is my Green Lantern power battery illustration as an animated GIF to display the importance of texture and lighting.
To do the style seen in my recent work I always build my base shapes in Illustrator first before moving into Photoshop. Illustrator allows me to get really precise with the shapes and colour, making sure those bezier points are working for me. But the texture and lighting work in Photoshop is what really brings these otherwise flat illustrations to life.
The first frame of the GIF is my flat vectors (and a bit of brush masking), and the second is with all the effects turned on.