I know I have touched on the importance of fit in freeform before. Freeform is not unlike working with fabric, it needs to sit in a way that best highlights the work. When I get to certain point in my design. Generally as I am starting to think about length and fit, I use draping techniques to ensure it sits correctly. The good thing about starting with a minimal base of peyote or no base at all is that you can go and zip up or add to sections that take away from the drape. I often hold my work up in front of a mirror but if you are lucky enough to have a bust or sewing form this is a great way too. If I am making a piece for myself I use a small bust with pins but this is not substantial enough for every body type.
As can be seen by this beautiful Zac Posen design, the way something sits can make or break a piece. Take my own current work in progress. You can see by simply pulling it together or pulling it out the drape changes.