To be honest - a hockey mask is going a little over the top... You want to be able to see, hear and move normally.
Safety goggles are wise, though not 100% necessary.
The most important thing I'd say is a hat and long sleeves... Most of the sparks won't hit you - it's only the ones that go straight up (and thus back down on you) that get you.
As per usual fire-spinning, avoid synthetic materials - keep clothing cotton based.
An added safety aspect to look out for is wind - always take into account the direction and strength of the wind. Even a gentle breeze can carry the sparks a long way.
Finally - stick to basics - weaves, flowers, windmills etc.
Definitely no buzzsaws

(And as I learnt, don't try and do a front-side seperation - the poi hit each other and sprayed sparks all over my face - not nice)