Pay attention to the yellow circle around your hero. It indicates the noise you produce. The enemy team will easily detect you if they get close. The sound of footsteps can be heard even behind walls! Keep quiet to go unnoticed.
Your speed also affects your shooting accuracy. Move slowly to start aiming.
To perform some actions, you need to stand still. Any movement during ally revival will interrupt the process.
And last but not least, beware of the death circle! When surrounded by the red light, follow the yellow X-shaped marker to save your life.