2. Reference Flash Don't put too much weight on the references. Look at your guide just a few times and then proceed to try by yourself
3. Interesting Perspective Your visual memory is a muscle, if you only draw a square from one angle you will be limited. By building shapes from multiple views, it will be easier to translate what you are looking at or even imagining.
4. Physics The physics of hands and cloth touching things around or even reacting to gravity helps to understand how shapes behave in reality.