Baiting is the simple trick of watching someone get shot to find a sniper's position. It's usually an unintentional recruit; but with speed and a good memory, you can take the hit yourself. It is also recommended to have a silenced sniper rifle in case you miss a shot. Another advantage is Increased Health (120HP) which allows you to survive a non-headshot hit from an enemy sniper, even one using a tier 3 rifle.
Some sniper rifles will leave a trail, simply wait till the enemy sniper fires at someone and watch where the bullet trail ends (where it is being fired from), at the end of the trail is the enemy sniper. This tactic is especially useful when the enemy sniper is hiding in shrubs or a building window.