If a target is moving make sure to lead it. If you are not making shots try to lead your target more. Also, if you are a skilled sniper try using the M40A3 over the M21. It has a slower reload time and rate of fire, but it has enough damage to kill a target in one shot instead of two or three. It also allows you to be less noticeable with less rounds being fired; so someone else cannot follow the tracer shot back to you. A good setup for the sniper is the Claymore perk, to alert you when an enemy is trying to close in on your rear, and either the Sleight Of Hand or Stopping Power, then Iron Lungs to give you more time to line up your shots.

Select three or four sniping points at every map through which you can rotate if one or two of your spots are "behind enemy lines" or do not offer desirable shots.

Find original locations. Everyone knows the generic spots that were designed as sniper positions on the map. Other skilled snipers will check these spots on a regular basis. One example is the uncovered bridge on Overgrown. Everyone checks that location first.

Do not go for headshots. As a sniper, you will get them, but only going for headshots will leave you with few kills and no ammo.

Do not camp in games that allow Killcams; the sniper or infantry man that you kill will most likely be out for revenge on his next life.

Try to find spots that provide cover (for example, not the middle of the road lying down). Sniping from extremely exposed locations will result in you becoming easy prey for more skilled snipers.

Be aware of your body position. Although you cannot see them, when lying down your legs will extend well behind you. Make sure you lay down so that your head faces your cover and your legs extend straight behind you and are not off to the side. Prone snipers can be killed by shooting them twice in the foot.

When using a Bari 50 Cal., do not point at an enemy then click as fast as possible. Shoot once, then wait for the effects of the recoil to wear off before you shoot again; otherwise you will shoot straight up.

Do not get discouraged. It takes a while to get used to the feel of your gun, the map, and the enemy. Experience is a very nice thing to have on your side as a sniper.