Jumping & Drop Shotting
Jump Shotting involves jumping around corners to surprise enemies, making you a harder target. Drop Shotting is going prone while firing, drastically reducing your hitbox. Both require practice but are highly effective in close-quarters engagements. Combine them with quick aiming for maximum impact.
Cover & Flanking
Always be aware of your surroundings. Use hard cover (concrete, metal) over soft cover (wood, thin walls) as it offers better protection. Learn enemy patrol routes and use flanking maneuvers to catch them off guard. Don't always take the most direct route; sometimes a wider arc can yield better results.
Grenade Usage
Mastering grenade throws is crucial. Learn to 'cook' frag grenades by holding the throw button, reducing the fuse time for precise explosions. Use flashbangs before breaching rooms to disorient enemies. Smoke grenades can provide crucial cover for revives or objective pushes in multiplayer.
Compare advanced combat techniques inCall of Duty: Black Ops II