Drupal 7 MultiStep Form
Helpful links for creating multi steps form are https://drupal.stackexchange.com/questions/135/are-there-any-examples-of-setting-up-multistep-forms http://drupal.org/node/717750, and http://drupal.org/project/examples.

I practiced multi step forms by getting the code of the form tutorial from http://drupal.org/project/examples, and added further steps; it works excellently fine for me.