I've had to deal with the sneaky type of player in jungle terrain alot. Probably because I used to be a really good one.
The key to hunting one is always to travel in threes. Keep close togeter, but not too close as to make a large target of the three of you. Usually you place the person with the heaviest weapon in the middle, and the other two stay either in forn of him or behind him. When in very dense vegitation never tread the terrain in a "Combing" manner. But Proceed very cautiously and as quietly as possible in a staggered line formation. Have one person with a short range AEG or M79 lead the formaton and act as "Pont" if any hostile were to open fire on the squad. If a shot is heard or a member of the three is hit, then the leader commands the team to take cover, be it prone in the tall grass, or behind a nearby fallen log or tree trunk. Because the hevay weapon gunner was place in the middle of the staggered line formation, he has much less of a chance of getting hit. From three of four possible angles one of the two other scouts proves a better possible hit than than the position he is in. No one memer is permetted to talk louder than a whisper when on patrol. Talking is a very distinctive sound, and can be heard from a greater distance than you think. Move slowly, and try to avoid stepping on anything that would make noise. Also try to prevent changing mags when there is no fire nearby.
If you do happen to know the position of the enemy before he knows your position, than absolutley do not shoot until you have made sure of a clear shot. This usually hapens when there is a small firefight going on nearby, and his focus is fixated on the nearby action. In this case, it is essential to move to a clear shot. Stay very low, and keep still and quiet. Wait for bursts of fire from the firefight to move, and do it swiftly. Usually when the enemy is unaware of you and you are in position, have either someone with an m79 or m60 open up on his position. the blast of the grenade, or the heavy incoming fire of the machinegun will startle him momentarily, and the rest of the squad can begin their assult. If the enemy happens to open fire on your squad, than cover should be taken immedatly. Now, when this hapens to most people, they just lay there in the grass or sit behind their log, and cluelessly ask eachother "where is it coming from?" This happens because of two reasons. The first is because they were not taking enough caution to keep their ears open to hear the shot. The second reason is because they werent trying to locate the position from thire point of cover. The most important part of doing a patrol in this terrain is to listen. Keep your mouthes shut, and your ears wide open. Teach yourself to distinguish the distinct difference between the wind moving the foliage, and a person brushing or stepping their way through the grass. Keep you ears open for all 360 degress around you. If you hear a shot or a step somewhere around your postion you should be able to locate its rough position immedtley as you take cover. After you have sufficient cover, very slowly raise your eyes above whatever you are hiding behind, and wait for the enemy to take another shot. If its a single shot rifle, then there are pretty good odds that the only exposed portion of your head is not going to get hit. But if its someone firing on full ato, then home in on the whining of the gearbox as quickly as you can, and duck your head back down. Usually you can tell the exact spot if you see a shower of white bbs flying towards you. Either wait for his highcap to WHIZZZ or poke you head up with your rifle already sighted, and lay down some covering fire before he knows what you are doing. Once you have him taking cover, then you have the upper hand. If the person with the heavy weapon is still alive, he should open fire and keep him pinned down while one of the other two makes his way around a flank and fires on the shooter from another angle. Usually It helps if everone has survived the initial attack to have the heavy weapon stay put, and the two others slpit and take the shooter's opposite flanks.