You don't work with fire, it works with you

or:
The flame is ready to be controlled only when you are controlled by the flame.
or um...:
When the fire is in your heart, you are ready to be in the heart of the fire.
(These are so easy to write!
)
Seriously though, my first burn was a week after I got my poi. I kept it very, very simple (crossovers were the most complex).
I started by getting a friend ready with a blanket and a bucket of water. I dipped my poi about 15m away from where I lit and twirled them. This is probably extreme but safe 
I think to start you have to be confident in what you are about to do, concentrate on what you are doing, and be prepared for any mishaps.
Just remember:
Only the enlightened fire twirler should be enlightened by the fire. 
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Iggity-aggity-oop-eh-eh! Ziggity-zaggity-zoo-ah-ah! Oooh-ooh-phblt! Eh-eh-ackh! Flippity-flappity-floop!