Master ease with this article from Threads #182 (December 2015/January 2016).

One of the best ways to create clothing that looks and feels good is to manage the amount of ease, not just in the garment as a whole, but in particular areas. This aspect of fitting is often overlooked, in part because there is no general formula for it. Learn how to incorporate ease mindfully when planning garments. Once you start seeing ease as a customizable design feature, you’re on easy street.