Remember: SAFTEY FIRST!!!!!
Useful links
Important F.A.Q.s READ THIS! A most valuable starter place for fire breathers/eaters.
Wikipedia.org - Fire Breathing
Wikipedia.org - Fire Eating
Firetoys.co.uk - A U.K. based company contains many tools for fire performances plus lots of other circus related equipment.
Bearclawmfg.com - A great site for a beginner, contains all the tools you may need.