I'm a sniper, and it's hard to snipe legit when ever sniper out there has chams on. So I turn mine on, now I know where everyone is sniping from, but I never look towards them I look around for at least 4 spots they could pop their head out, I even turn my head to look somewhere else. I have my radar on so I know when they moved. Once they've moved a little fast I turn back to one of the 4 spots and pretend I didn't see him. I send out a shot and, for some stupid reason, they always pop their head thinking I'm using a bolt-rifle.
You can really tell when someone is using chams.
1: You can notice they follow your movements where ever you go.
2: If you turn and run the other way they move to another target.
3: If you decide to come back they'll follow your movements again.
4: Other times they'll throw a grenade and say it was random, most of the time it's not.
5: When you get too close to them they maneuver so they get the advantage; which for me doesn't work most of the time, if I see you I'm shooting.
But yeah, if you don't do the noobish things above, you're good, and like ROUGHS3X said, if they're in a tight area never run to their location like your hunting them. Sometimes I like to pop a grenade in my hand and let the person kill me. If they didn't notice the grenade, boom. If they did they'll run out in the open and hopefully get shot at.