Gestures with an object – in context
Holding an empty cup out to an adult with a milk carton to request something to drink
Pushing a plate with vegetables away to reject something
While playing with blocks, holds a block out to the adult to request help to build
Brings a book to an adult to request read

Gestures without an object
Points to objects to request
Holds hand out with palm up to request what other person has

Photographs
In addition to a photograph, another technique is to cut out around the object which will give the shape information, usually referred to as TOBIs (True Object Based Icons)

Detailed graphic
This would be similar to detailed clipart or cartoon drawing

Line Drawing
Stick figures

Objects
scale model to represent larger object

Signs
Formal sign language

Words
Uses verbal words to communicate meaning

Keep in mind that skills will overlap and not be replaced by preceding skills.