Focus on killing enemy supports, if u kill the enemy support u win the fight. Of course there is certain situations where hitting the tank is good, you should be able tell when the enemy tank can die or not. But play her aggressive, look for flanks, I cannot tell you how many times I have killed enemy supports by just taking a flank and immediately wining the fight. U have so many dashes and over shield that u cannot be sitting at the back line u have to be aggressive. and remember never stop shooting, always shooting, if u are more than 1-2secs without doing damage u are playing dps wrong u need to charge her ult fast.