The prior poster is correct in some respects, but, I think, misses what you were going after. I assume that you'd like to have a 30-or-so page document named, "Document.pdf," separated into 30 different documents named, "Document-001.pdf," for page one, and, "Document-002.pdf," for page two, etc. After much experimentation, here's how I was able to get Automator to accomplish this goal. Look for these items in the Automator window panes on the left-hand side of the Automator workflow window:
1. Ask for Finder Items (Library:Finder);
2. Render PDF Pages as Images (Library:PDF);
3. Rename Finder Items (Library:Finder);
4. New Folder (Library:Finder).
I know that the lack of specific commands to save items, and to pass them along to the next step is confusing (at least it was to me), but this really does work. Place the workflow items in the order noted above, and you will get what you described you were looking for in your intitial post. What's even better, this workflow will name your new files sequentially when you click the correct options. I recommend that you play around with the options for each workflow item to make the workflow more robust, but I'd stick with basic order noted above.