There is one thing that factors into how contact would likely take place, but it's a guaranteed Rule 14 if I typed what it was.
Regardless, there is one thing that I will say; if contact is made, people will panic. It's almost guaranteed that there will be conflict. If not with one another, would be with them. More than likely it will be both.
Trying to be in their position; unless the planet is worth it, contact is just not something that would warrant the time and resources right now. It would cause panic and unrest, and likely conflict.
If the planet is worth it, a Conquest type move would a better option vs some kind of peaceful method at this time. People are far too closed minded, and far too divided. Talking will accomplish little and will very likely destabilize the planet further, making it that much more difficult to accomplish the goal.
With that all said, it's only a matter of time before contact is made. Only idiots think we are the only race out there. This galaxy alone has be around longer than the solar system we inhabit has existed, not to mention the other galaxies that are out there. Truth be told, an intergalactic race would worry me more than an interstellar race. Reason is quite simple, one possesses the ability to travel between galaxies, the other does not.