First contact with an alien species is a tricky situation to deal with. When handled well, these aliens could become humanity’s greatest allies, helping us to take our place on the galactic stage. When handled poorly, humanity might wind up looking for a new home, if we’re particularly unlucky. And of course, that all assumes these aliens have shown up with peaceful intentions–there’s always the possibility that it’s a trick to take over slowly, or there’s cultural differences that can lead to major misunderstandings.
For the sake of this list, we’ll think of this as the aliens coming to us, but a lot of these points are just as effective in a Star Trek situation where we’ve gone out seeking new life and new civilizations.