Animator Tomek Baginski gave a talk on planning a 3D animated short film at the 2007 Ottawa Animation Festival. I transcribed this from my notes.

• 1. Concept Art
  Everything that will be modeled is drawn first.
• 2. Storyboards
  Shots are planned out.
• 3. Animatic
  Shots are timed. At this point the picture is locked.
• 4. Modeling
  Front, back, and side views are drawn and placed on 2d cards.
• 5. Textures
  Textures should be at least double the final image resolution. That means 4K textures for an HD film, and more for closeups.
• 6. Background Painting
  Use as many 2D backgrounds as practical, moved on cards to preserve parallax motion. For a consistent look, you can build backgrounds in 3D, choose camera angles, and render out still images. You can also build simple 3D scenes for reference, hand-paint details on the reference image, and then project the result back onto the original 3D geometry.
  
• 7. Choreography
  Figure out your rigging requirements. Try shooting live-action reference footage.
• 8. Rigging
  Use bones for the jaw and blend shapes for other facial expressions. Use jiggle and cloth deformers, but sparingly; try to sculpt as much detail as possible into the model.
• 9. Lighting
  Rely as much as possible on three-point lighting with simple, clean white light, and color-correct afterwards in compositing.
• 10. Depth of Field
  Identify which shots will need depth-of-field effects. Unless you have to match live-action footage, use simple blur effects in your compositing program instead of true 3D depth-of-field effects in your animation program. They render faster and make little difference for most shots.
• 11. Render
  For extra flexibility, render out multiple takes with different lighting setups or special effects. If that takes too much time, render the character animation cleanly and experiment with effects on a 2D background plate.
• 12. Composite
  Try to give yourself as many options as possible in this final stage. Color-correction and other fine tuning is often much faster and easier in 2D.