My 2 cents/pence:
Costume is a huge step in the right direction. With a good costume you're looking like a pro before you've even done anything!
Work out your set to build from small to big (either in size of fire or personal favoutire) so that you finish with a solid ending.
Do a search for entertainment agencies and send em your promo (oops! that's step 2).
Come prepared with all you ropwn safety equipment, be aware of the space and floor surfaces you need to spin on, don't be messy when fueling up, try not to spray fuel everywhwere, keep your head up and engage your audience when spinning and smile

I kinda agree with what Charles says about go out busking a few times to ge tin the groove of not just having a spin but actually performing, although you might find it hard to busk fire in the uK (you're so lucky charles!)....
good luck!
dave