Call me a pessimist, but in my speculative opinion:
The most likely thing to happen will be that they consider us uninteresting and completely ignore us.
The second most likely thing is that they will consider us or our planet a natural resource of some kind and will take possession of whatever they need. We will be to them as the members of the animal kingdom are to us.
The third and least most likely thing will be that they find us interesting after all, will respect our life and become benevolent friends.If you consider our attitude toward life forms that are below us in the natural order, and consider our position below aliens in the natural order, my conclusions are compelling. We naturally conclude that the experience of animals in this existence is insignificant compared to our own, and aliens will most likely conclude the same when comparing theirs to ours.