Hint: Free yourself from capture:
When you are shot two times (four times with kevlar vest), or pass out from gas, you will be captured. At this point, you will be briefly taunted, and then asked if you would be willing to trade your freedom for one or more enemy agents. Choose yes to agree. If you choose no, although you will not have to re-arrest someone, picking the handcuffs takes time. Note: As soon as you move your character, an alarm will sound and guards will start to arrive within 10 seconds.
Hint: Throw the enemy off your trail when discovered:
To throw an enemy off of your trail after being discovered or after lockpicking the handcuffs, close all doors behind you. Since the enemy agent's AI is programmed to look for open doors first, you will gain a small amount of time.
Hint: Grenade warning:
There are three types of grenades in the game: fragmentation (frag), Stun (flash-bang), and gas. Never use the short throw command for a frag or flash-bang grenade, as you could suffer damage by being too close to the explosion. Also, frag and flash-bangs will set off an alarm when used in a building. Since gas grenades do not explode and are silent when they release their contents, you can use them without fear of setting off an alarm -- just make sure that you have a gas mask equipped.
Hint: Using grenades as booby traps:
If you are breaking into a building to make an arrest, search the entire building to find a possible second exit. Before you make the arrest, litter your escape route with frag and flash-bang grenades to be set off by remote control. Please note that the remote control will set off any and all grenades you have set for remote control -- make sure that you are nowhere near a grenade when you use it.
Hint: Disguise yourself:
To obtain an enemy disguise, just shoot a guard before he can set off an alarm. This lets you 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 flashing red, there is an alert and you can not get a disguise. If it is a solid blue, the alarm is off and you can get a disguise.