No quicksope bullshit to start with! haha. But on a more serious note, what you want to do is play a semi-aggressive sniper role. Dont spend a long time aiming down sights, just shoot as soon as you think the enemy is in your sight. Dont stay in one spot but at the same time dont go rushing into high traffic areas. I actually made a video on this exact thing, please check it out and let me know if it helps you any!
My Favourite Class Setups! - Sniper Rifle! (Gameplay/Commentary) - YouTube