It's easy to not get killed by snipers. Once you die once, you know where you got shot from. So when you spawn, just avoid putting yourself where the sniper can see. If they are good, they know the line of sights and probably will kill you a second time. However, that just helps you pinpoint their sniping post. Just spawn, scope in with your DMR to their spot and start putting shots on the sniper, and that'll rattle em a bit, giving you time to run to cover. Then you can hopefully duck and dodge to somewhere you can engage the sniper close range. Provided they aren't sick at close range no scoping, you should hopefully be able to take em out.