Ruckus with Wrecker can literally melt your shield! Formidable might be a good alternative to Aegis, since it gives you healing when your shield is abscent, but only once every 40 seconds, so enter the fight at the right time!
Skye has the highest DPS in the game when at close quarters. Sometimes it's better to turn around and block her shots with your shield or Charge away. Judge from where the most damage is coming from.
Save your Fireball when Seris is healing her tank. Combining that with Cauterize on your flamethrower, your tank will get healed less, so he will require more healing attention, as such, reducing the survivability of their tank and other teammates.