Registered and eager to start - but where? Wool, cotton, flax, silk or something else?

I have now got to start on my portfolio of samples. A range of yarns in various thicknesses, appropriate for the fibre being spun and the use to which it will be put. Singles and plied yarns to be included & all hanks to be at least 100m in length.

As I usually spin wool, this would seem the most sensible place to start - but there are so many combinations to consider:

Wool - to be spun woollen and worsted as appropriate.

1. short wool and down
2. long wool and lustre
3. mountain and hill

I am beginning to think that it may be easier to start with flax!