I work as a tutor for ASL at a community college, and I can say that you are not alone in being confused with what classifiers are all about!
The greatest thing about classifiers, which robbielyn eloquentally said, is that you can be creative using classifiers! Most of the time there is no right or wrong rules about using classifiers, as long as it makes sense.
To start off the story for Riding Hood, one can set up two characters and use roleshifting. To the left, show the height, then hair length, texture, freckles?, and then the most important thing, describe the hood and how the girl is wearing it. Then to the right, you have the mother telling her to go to grandmother's house. Describe the basket that the mother put together, what food, etc... Then giving it to the girl and pointing to outside, and scolding to the girl, saying path dangerous, not walk off. Back to left, act as the girl is listening innocently. (This is only the first part. You can describe how the girl acts going thru wood, etc...)
Sometimes classifiers needs to include a lot of acting instead of words!
Hope I helped somewhat.
Good Luck!
