Recognize what is out of place or unusual:

Unusual activity can include people acting furtively and suspiciously, avoiding eye contact or departing quickly when seen, or individuals who are at a location without a reasonable explanation or are doing something suspicious.

Analyze the situation:

Once you have recognized a situation as being suspicious, you will need to analyze it. By analyzing the situation, you may be able to rule out the suspicious activity as normal. For example: a UPS truck has been down your street three times, however, it is Christmas and they have several trucks making deliveries on Christmas day in your area.

Report it:

Once you have gone through all of the steps and you still feel that the activity is suspicious, report it. Once you have reported the situation, you should write down all of the details and why you felt it was suspicious. The written details will be helpful if you are asked additional questions at a later time.