What matters during an Alien Invasion?

This is considering one of the most recited, and certainly most unlikely, scenario.

That of sentient living beings from other planets landing on Planet Earth with the goals of and/or
1. subjugate the local populace
2. eliminate the local populace
3. extract resources.

What happens, should those overt operations occur?

1. Where the landing pods come down (the alien landing craft).
2. Who is near you (which human factions or groups).
3. Which technology do you have available when they arrive?

As a human, considering that the goal of the alien faction might be to wipe out humans to have the planet for themselves, their offers for an alliance cannot be trusted.
Just like the Conquistadors, who aligned with local groups who opposed the central governments in the capitals and then were able to eliminate the head of state, thereby toppling the civilization, and eventually enslaving all remaining humans to slave and die in their mines, the other faction would make use of the paradigm of divide et impera.

Which means, they would look to cause rifts within the cooperating groups of humans, and to extend and exploit them if possible.

That does not mean that conflicts should not arise. Adversity breeds progress.
Important is that communication within humanity is open and respectful.
It can become stressful at times, but even when expressing opposing viewpoints, all parties should remind themselves and each other that they respect and appreciate each other.

On that basis, most preferably, should contact with alien factions be made.
As ambassadors of a united humanity.

Perhaps the best idea would be to send messages back and forth, with the visitors remaining off planet for the time being.
If a visit is negotiated, it would then be on the terms of humanity.



Perhaps a sane form of competition can be achieved.
Since the domain of the alien faction is currently, confirmedly, the sky and beyond, while humans are confined to the surface of this planet, perhaps a deal can be struck by which either faction takes control of the surface on the bottom of the oceans.
This would allow for a more nuanced solution to a problem the open arrival of alien visitors could pose.