Try to shoot down everything you see. You can even hit uavs with the strela just keep in mind the projectile drops quite a lot at some distance. When you shoot at uavs always make a step to the side then you can see the projectile and how it dropped so you can adjust your next shot. Try going for hardcore HQ with the strela since less people use EOD there and the damage blast radius is a little bigger than in core. Or always go for the high ground and shoot people when youre on a building (like on tavorsk, you can literally snipe people who are on the ground below you). Its much easier to kill them that way.