Use the word indicative when you want to show that something is suggestive or serves as a sign of something. Your willingness to help out with the charity is indicative of your generous nature.
The adjective indicative is usually followed by the word of. After being caught in the storm, you protested that the current condition of your hair and clothes were in no way indicative of your normal grooming habits. Instead, you argue, your appearance is indicative of your work ethic, since you braved wind, rain, and sleet to get to work that day. Did you know that some experts say the rise in skirt hemlines is indicative of economic recovery?