You are OP in early game. Upgrade second skill first, to do a lot of damage to enemies. Kill minions to level up. Don't attack turrets, as your attack speed is slow. Don't get too close to Franco or Zilong, as they can reel/flip you into the turret zone, where you will be slowed down and finished easily. Beware of heroes that can shut your abilities down.
Stay with one other hero, and tank for them if needed. Try to get some good hits in and finish your enemies with Revenge Strike. Penalty Zone is very useful for crowd control, as most will panic to get out instead of trying to attack you. When using second skill, be very careful as many heroes can stun you and stop your skill. Make sure you have plenty of physical lifesteal, to keep you alive in a crowd of enemies.
Stay with your group, don't try to solo unless you are sure what the other enemy heroes can do. Getting stunned will get you killed. FLAMESHOT is a good skill to equip, as it knocks enemies back. It has saved me in more than one occasion. FLAMESHOT can also be used to snipe enemies off, although this is more useful in Early Game.