How to make a puppet Stand?

You can make it higher like Mickey Mouse type voice. (This is called a falsetto voice)
You can make it lower like Santa Claus. (Ho, Ho, Ho)
It can be gravely like Oscar the Grouch. (Hey, who knocked on my can?)
Sweet and soft like Snow White.
Bumpkin, like Goofy.

The most important thing is to make it different than your own. This will make your puppet stand out on its own. You also need to give your puppet a character. Here's a link to a site that teaches some ventriloquism: http://www.axtell.com/learn.html