On the South of France level (multiplayer) you can get up on a rooftop which is ideal for sniping, and it's hard to spot you (unless other players force models with a bright orange skin).
Firstly, go to the buildings that have the bridge between them. You want to be on the balcony nearest the telegraph pole with the wire on it that leads to the roof. It takes a bit of practice but it's possible.
1. From the balcony, jump up onto the railing.
2. Stand up (you'll be crouched when you get up there).
3. Use the cross-hair of your weapon to line yourself up for the jump.
4. Now holster your weapon.
5. Run to the end of the railing and jump to the wire.
It may take a few tries to get your distance and timing right. Once on the wire, draw your weapon again, face right and draw your weapon, again use your crosshair to line up with the wire and walk to the rooftop. You don't need to use the crosshair once you're used to it, which makes the action a bit quicker.
Note: This is extremely hard to do when under fire, so try it only when it is quiet.