Best tips so far are to find a synergy between storm seals. Freeze primers and electric detonators so they don't thaw but still get combos. An AR with elemental boost is great as well.
Be kind to your fellow freelancers and don't do chest runs. Some of us would love to start at the beginning of an instance instead of the end .
First of all, clearing turrets and non-shielded mobs (controlling by freezing them if playing on Storm). Then focusing on shielded enemies, prefer using for that Thunderbolt of Yvenia or Divine Vengeance.
The rest of the time is to support teammates, aviod suicidal attacks and active maneuvering.
As previously said,
GM1: Kill everything. Literally everything. The mobs are squishy enough to solo anything.
GM2 & 3: Work with your team for combos. Use the Mic to talk since there is no ping or text chat...yay. Still kill everything. Had a scorpion drop a MW so that was cool. Try and prioritize turrets when able.
Mostly already said, but I will add the following:
Remember your Javelin's special and use it. Esp good for Interceptor spreading ice or acid.
Staying in the circle makes things quicker.
Remember to dodge (or shield)
Interceptor, triple dodge then double jump to triple dodge refreshes shields.
Interceptor when your shield has gone you should already been on your way out (see above)
Ultimate rezzing can be a very good use of ultimate.