You don't need to do a detailed Drawing as long as your measurements are right. (Link to video)
Here's the sequence, drawing with the brush:
1. Warm-primed canvas
2. Careful measurements with brush.
3. Big areas blocked in.
4. Subdivide small forms.
5. Details and accents.
2. Careful measurements with brush.
3. Big areas blocked in.
4. Subdivide small forms.
5. Details and accents.
