Mission tips
Always shoot hinges or locks instead of blowing them because it is quieter. Always crouch behind objects and make sure that your squad is with you shooting or you will easily die. Shoot through car windows, as they are a useful shield.
P.E.C mode specialist rewards
Combat Medic
Starts with: Pistols, Sub-Machine Guns, First Aid
Level 5: Adrenaline Boost
Level 10: Light Armor
Level 15: Nerve Gas
Level 20: Feild Clinic
Level 25: Shotguns
Level 30: Free Gas Mask
Level 35: Medium Armor
Commando
Starts with: Pistols, Assault Rifles, Toughness
Level 5: Medium Armor
Level 10: Heavy Weapons
Level 15: Grenadier
Level 20: Ballistic Shield
Level 25: Heavy Armor
Level 30: Enhanced Recovery
Level 35: Recoil Control
Engineer
Starts with: Pistols, Shotguns, Electronic Keycard
Level 5: Light Armor, Traps
Level 10: Hacking
Level 15: Medium Armor
Level 20: Deploy Turret
Level 25: Sub-Machine Guns
Level 30: Firewall
Level 35: Demolition Expert
Spec Ops
Starts with: Pistols, Submachine Guns, Surveillance PDA
Level 5: Sensor Jammer
Level 10: Light Armor
Level 15: Assault Rifles
Level 20: Medium Armor
Level 25: Knife Attack
Level 30: Adv. Heat Sensor
Level 35: Critical Hit