Some good countersniping locations:

Here are some good locations for taking out those opponent snipers.

Crash:
-At the Marine spawn, take a left and go towards the corner, with the grassy hill at your left. Turn and face the building and zoom in with your scope. Aim your scope left, slowly, until your crosshairs are in between the building and the pipe (pipe is left of the building). Enemy snipers are hardly ever conscious of this spot as they are more focused on movement in the grass behind you and even if they do see you if very hard for them to hit you with a shot in between the pipe and the building from that distance. I usually start every game off at this location as a marine. Watch for the red hat to pop up in that sniper building and also, up the ally on the left side by the green car, there is a barrel that opfor usually try to go behind for cover. I can get up to 3 headshots right off the bat for this location.

-Next one is the building immediately to the right of the marine spawn. This is more known than the other spot on this map, but still many people don't pay attention. Go upstairs in this building, but stay under the roof. There is a window facing the 3-story where you can hit people on the third floor. If you stand on the windowsill of that same bulding you can also hit unsuspecting people running through the first floor of the 3-story towards the marine spawn.


Strike:
-This is one of my all time favorite sniping spots. From the marine spawn go down the hill and take a left into the small courtyard. Go into that building there and then move to the room with the window in which you can see the catwalk and flower shop window. From that window move all the way back and go prone on the floor. If you happen to be a marine, you are almost invisible lying here on the floor and you get a clear view of anyone peeking out that flower shop window as well as anyone walking on the balcony/catwalk towards you. Just don't stay here for long as there are far more openings than claymores and enemies are sure to come after you for revenge.


Crossfire:
-The sniper building at the bottom of the hill (with the pile of rubble in front of it) is almost always checked by enemy snipers. However, they mainly check the open windows and second floor of that building. If you go on the first floor you can stand on a counter and be covered in front by a column. The top part of the wall here is blown off so only your head shows. You get a clear view of the building at the marine spawn where snipers go as well as the one to the top and left of the hill with the balcony. Be wary of ghosts coming through (a claymore by the green car or even by the ladder in the building next to it is a good idea just as a warning for when someone is coming). Also watch out for people with LMGs or deep impact spraying the wall in front of you trying to get revenge.

-At the marine spawn, go towards the building at the corner on the right with the balcony. Outside there is a car ( i forget which color). Jump on the car, then on to the piece of the wall directly in front of you (facing down hill) then jump onto the awning there. Peer around the corner and you can take out enemy snipers at the bottom of the hill. This is a good starting point. Be wary of rushers moving to your left by the bus trying to hold that position as well as ghosts moving through the left buildings trying to take out snipers behind you. This is also an easy way into the second floor of that building and you can avoid claymores that the opposition might have placed on the stairs.


Wetworks:
-At the spetnaz spawn, go into the sniper tower there ( the one with the two sets of stairs in the back, not the one set of stairs inside). Move either to the left or right but try and stay behind the building, Go to the side of the building, but still behind it and stand. Turn on your night vision (easier to see the heads) and aim your scope towards the opposite sniper tower. Look for enemies peering over the railing on the sides of their tower but make sure you keep most of your body covered. Enemy snipers will be too focused either on the deck of the ship of the many windows in your tower to notice you and you can get a couple headshots, just make sure you move back to cover if you miss and then go over to the other side of the building and do the same from there. Once you take out anyone on the sides there, move outward slowly and check for heads by that large pipe/mast on the other tower, many snipers like to use that for cover, but if you're fast enough you can take them out before they see you. Just watch out and don't make sudden movements.


Pipeline:
-At the SAS Spawn move directly forward staying on the right side of that waist high stone wall. Go to the end of it and go prone. You can see directly into the windows of building 1 (the one immediately next to the trainyard). If you maneuver your body a little bit, you can also see the corner part of the roof where people like to jump from the small building with the ladder, onto the roof and into the window on the trainyard side.

-From the Spetnaz spawn, head into the turret building, but remain on the ground floor. There are a few boxes and barrels down there. Hide behind them. There are a few cracks in between them that you can aim your scope and remain crouched. This gives you a clear view of the hill as well as the main road in between buildings 1 and 2. Look for movement on the hill (most people don't snipe there any more but you can still find one guy there every so often).



I know I didn't cover every single map, but these are the ones with the absolute bests spots to counter snipe. The rest of the time I usually improvise. I hope these tips helped you and if you have any to share please do.

damn nice guide moved to userguides

Another one I forgot to mention...

Ambush:
-At the Opfor spawn, go to the left and creep around the middle building. Immediately at the corner of it there are two concrete barriers. If you go prone here you can peek through the slot in between them and get a clear shot at the blue sniper room on the Marine's spawn side. This spot provides you with plenty of cover from the front. Just watch out for random grenades.