Look at the setting and the character's state of mind, and then think about what you want the reader to see. Is there a descriptive symbol or two that works naturally within the scene to help foreshadow an event or theme, or create insight into the character's emotional plight?
Seasons: Spring, Summer, Fall, Winter
Dandelion fluff on the wind
Melting snow or ice
Snake shedding its skin
The Death Tarot card
A row of school pictures
12 step programs
Human growth cycle (height/weight changes)
Innovation & inventions
Drug/alcohol use (altered physical/mental state)
Shape shifters (fantasy)
The Greek letter Delta
These are just a few examples of things one might associate with Transformation & Change. Some are more powerful than others. A Butterfly's cocoon is a strong symbol, and likely will not require reinforcement. However, Crime could stand for a number of different things and may not foreshadow Transformation & Change on its own. Let the story's tone decide if one strong symbol or several smaller ones work the best.