O  - Observe signs of surveillance, look for photographing, recording and monitoring activities, such as: Persons making drawings diagrams or maps. Pay attention to persons watching or those with unusual interest in infrastructure: power, water, plants, bridges, schools, stadiums, shopping malls, public transportation. 

B -   Be aware of unusual inquiries regarding important places, workers, or operations  dealing with power, water, plants, bridges, schools, stadiums, shopping malls, public transportation.

S  -  Security may be compromised by walking into restricted areas to gauge response  or test the strength and weaknesses of security in a building or area. Frequently test your systems to assure they have not been compromised.

E -  Engaging in the surreptitious acquisition of supplies such as identification, stealing uniforms, forging IDs, passports. Acquiring firearms, ammunitions, explosives, or bomb making materials. Immediately investigate thefts of these items.

R - Remember to be on the look out for suspicious or out of the place behaviors. Asking unusual questions or being in places that seem out of place - Trust your instincts. If it does not look right... It probably is not. - REPORT IT.

V - Very likely to make dry runs where they put people into position and move them  

around according to the eventual plan without committing the act itself. 

E - Evolving plots will try to get terrorists into position at or near a target.  Sometimes

leaving something behind and removing themselves from the premises, such as a