From my Academy of Arts Online painting class:
Simplified Painting Process: Review
- Establish your idea.
- Do a variety of compositional thumbnail sketches.
- Gather necessary references.
- Develop a more refined sketch.
- Draw out your composition on final canvas.
- Check for drawing errors.
- Develop lay-in.
- Check for drawing, color, and value edges.
- Evaluate your overall lay-in.
- Fix or correct any areas that bother you.
- Begin to develop modeling within forms.
- Look for color modulation or variations within areas.
- Stand back and evaluate what you have done.
- Change anything, correct or add to what you feel you need.
- Continue modeling other areas.
- Again look for color subtleties.
- Do not over refine any area.
- Re-evaluate what you have done.
- Fix any problems.
- Continue modeling and re-evaluating and much as necessary.
- Make sure to keep areas a bit understated.
After several passes you will be ready to finish the painting.