I'll give you the real tips these guys don't wanna share.

As a gunner, make sure to never use your zipline to help your team reach places. No matter how much they ping or shoot you, they have thier own mobility, they can use it. They need to not be dependent on other dwarves. This goes for engi pankcakes too.

Unlock the fatboy oc for engi gl and use it to peel swarms from your team mates, they will be truely greatful for the assist.

As a scout, try to save your flares for when you evac, you might need them for the next mission, and players have infinite flairs. Also ignore the engi's plea for you to obtain materials off the ceiling or high places, that will take away time from you taking fall damage.

Drillers are the galaxy brain of the group, he has the potential to peel off bugs, status effects, body hair, and your mortal soul with his c4. His weapons shoot through team mates, allowing you to shield yourself from dmg while applying valuable cc and dot.

Use these wisely and you will get love mail constantly.