Positiong is everything. I also hate keeping the rez even though everyone says it's something that we should keep. If i have noone around i will rez another team mate. Damage boost. It's very important. I also check timer all the time. I also keep the ult till the crucial moments and just fly as high as possible and heal and damage boost. Try to keep your team as much as healed as possible and move around. Be careful of Widows and Pharahs. Use your stuff and gun to hit the opponent. Not just shooting. Hit them.