To acquire an enemy disguise, just shoot a guard before he can set off an alarm. This allows you to walk among the guards without them knowing who you are. Make sure that you do not look them in the eye, or they will recognize you and set off the alarm. Note: You can not get a disguise after the alarm is set off. You must leave and re-enter the building or remain undiscovered until the alarm turns off. You can tell if the alarm is active by looking at the border of the screen. If it is a solid blue, the alarm is off and you can get a disguise. If it is flashing red, there is an alert and you can not get a disguise.