Mind if I weigh in a little on this one? Please save yourself the aggravation of buying your balloons from Oriental Trading, the local party store or Wal-Mart. Scruffy is right when he said that there are two main brands that are used in the twisting community: Qualatex and Betallatex. There is a reason for this --- Quality and consistency. In order to become proficient with your twisting you need to have balloons that you can count on. It does you no good to get 85% done with a sculpture and have a bubble start to leak.
There are a number of places to find instructions for balloon creations. I have been collection a few and placing them in the Balloon section of the forum. There are a number of video clips (the quality of the sculptures is pretty good the filming leaves something to be desired) at
The Balloon Animals Blog There are instructions and thousands of pictures of creations at the motherlode of all balloon sites
Balloon HQ - Educating the World About Balloons and Balloon Art
You as the entertainer can control at least to a degree what the audience wants, but it takes experience.