Stop staring at your mobile phone and be aware of what is happening around you. This is the top tip security expert Danny Chan has for how people can keep a lookout for possible dangers or threats.
This is especially important if you are travelling abroad and in unfamiliar surroundings, said Mr Chan, Marriot International's Asia-Pacific regional director for global safety, security and global risk management.
"It's like when you are driving - you don't just look at the car in front of you, you look five cars ahead, to the left, to the right, and behind you," he said.
Another tip is to take a mental note of exits and places to hide when entering a room or place. Do this regularly enough and this "basic situational awareness" would become "second nature", he added.
High-end hotels have been attractive terror targets for terrorists, and Marriott hotels have been struck over the years, such as in Jakarta in 2003, and in Islamabad in 2008 - which is why such awareness is something Marriott International tries to inculcate in all its staff.
The hotel started its "See something, say something" programme in 2010, where all staff are encouraged to flag suspicious items or people. For instance, they are told to look out for people taking pictures of CCTV cameras, raise the alert if they are asked about hotel security deployments, or if they see strangers walking around in staff areas.
Housekeeping staff are told to look out for maps with circles drawn on them in rooms, as well as large quantities of material that can be used to make bombs, such as nine-volt batteries, nuts and bolts, and nail polish remover.
"It doesn't matter how many security staff you have, they are not going to be everywhere all the time... Everybody needs to get involved," said Mr Chan. He notes that a hotel has 600 employees on average, but only 15 security personnel.
In the same vein, security agencies cannot be everywhere at the same time, so this is where the public comes in. "Every one of us has to play our part," he said.