Most important!!; Join a moon clan asap. Get the kunias. My biggest issue with this game is the shitty difficulty scaling. After a certain point there is no challenge. Nothing left but obstacle courses and PvP.
5 real modes:
Mass Murder - Defense and survival, for mods and common resources.
Parkour - finish mission asap, skip fighting, for credits. Volt is recommended.
Boss - varies, mostly ends up being parkour for BP and resources?
Serious tactical challenge - almost never happens. Lucky nightmare matchup.
Where the heck am I - most story missions