All I meant is that it's rather dangerous for someone very weakly armed in close combat (a sniper, in this instance, but other examples include a Piat gunner (with just a pistol) or a tanker, again with probably just a pistol) to try and take a flag unsupported. Obviously, there are tons of variables - take one of the higher flags on Crete in 0.7, and you could be completely out of sight behind the dunes and hills in 10 seconds. Other flags, however, require you to be much more cautious. Obviously, sometimes there is the nice bonus for a sniper to be able to switch his kit to an MP40/Tommygun kit for the 10-20 seconds he's at the flag, and then switch back to his scout kit, but that is not always an option.
Another, and probably obvious tip is to only use your scope when it is absolutely necessary. Some of us have been tricked by sniper movies to think that you should always be looking through the scope and aimlessly staring around the battlefield, but again, obviously, this isn't the case. You are much better off, when looking in a general direction for a target, to switch to a smaller weapon (remember, the smaller you can make yourself, the better - you should only have your rifle out (i.e the biggest weapon you have, in terms of physical size) when you have acquired a target).
I would also suggest you don't be too proud to, if the servers are too full or too empty, to go into single player mode and find some good spots.