I would add to this list knowing the fabric medium, because unless you know about the properties of fabric (selvedge, bias weft, warp, stretch and thread count) you will come across many difficulties when making your final creations.
While costuming for soft sculpted cloth figures lends itself really well to folding, pleating, fraying, gathering and layering fabric, it is also possible to use these techniques in other innovative ways.
I used Trapunto for veining the mermaid tail and to create a root system on the Earth figure's feet.
Needle-sculpting facial features is much like quilting: (i.e.to pad and stitch ornamentally)
It can also be used to create designs on the body and limbs.
< This is Cushionella's hat, complete with frayed embellishment around its edge.