Winkling someone out of solid cover is a tricky task, as they will
only show a tiny bit of themselves. To get easy kills it is best to
get several players shooting at the same person from different angles.
Defending against rushing
If you are hiding behind a piece of cover and someone who knows you
are there runs round the side of it whilst firing at you, there will
be a very good chance that you will be shot first, even if you have
been waiting for it to happen, because there will be a split second
delay before you start firing, and also it is hard to track a fast moving
near target. This danger is magnified if they could run round either
side so you have to watch more than one direction at once. The best
protection is to have another team member further back covering you,
who will have ample opportunity to both warn you that someone is coming,
and hopefully to shoot them as well.
Deliberately trying to attract fire in order to draw out an opponent
for your friend to shoot is a surprisingly productive tactic. Sometimes
cover will mean for your opponent to get an appropriate angle to fire
they must expose themselves from another angle. Windows are an obvious
example of this, where to fire at someone close to the wall that the
window is in, it is necessary to expose significantly expose yourself
to anyone who is further away from the window.
Often when a player shoots at an enemy they expose themselves to fire
from other enemies. Teamwork can reduce this risk if their team mate
fires or covers potential enemy risks. Tell a team mate who you are
about to fire at and which direction you need covering from.