The best spot to be is somewhere on the side of a mountain. Think about it, when your base is getting sniped, the first thing most people do is scan the tops of the mountains for anyone trying to peek over the top. By being on the side of a mountain, you should have enough time to take them out before they spot you. This is one of the biggest mistakes new snipers make. Respect another snipers position.
Attention is the number one killer of all snipers.
Having more than one person sniping from the same spot certainly draws attention. I'm not saying you have to go too far, just don't stand right next to them. If your on a hill, try moving to the other side of the hill where you cant see him. Snipe from a position at a further distance. When the enemy gets wise to the sniping direction, they will kill him then assume he was it.