an alien race, from another galaxy would probably observe us first, it would keep contact down to a minimum, maybe a handful of earth people would sight something,abductions, i don't know, it's possible, however the alien race would observe us.
they will eventually make some sort of contact, i imagine the best way to engage with us is through the internet, blogging. think about it, perfect way to begin an expression of it's thoughts, perfect way to have a small percentage of humans read it, follow it perhaps. maybe it would give itself an identity, captain mission, a time being, approaching parvonis mons by balloon, the list is endless, the alien blogger would write a few posts and gradually gain a handful of followers, this would grow and eventually there would be a community. the community would generally accept the alien nature of the blogger, some may question it, but there are plenty of people who would accept on faith the writer is alien. now the alien can engage with humans, get a human perspective, learn about us and ask direct questions about us, observation is the first stage, engagement the second and then contact.
imagine how it would play out, imagine the conversations, the types of people who would follow the blog, a diverse collection from around the world. perhaps you are part of that group. 
perhaps the alien will pretend to be human, the first few years would be spent just fishing for people, a diverse group, the writing would be different, strange experiences, creative, bizarre, perhaps silly, but within it there may be clues, and gradually as the years pass, some other kind of messages, maybe eventually full disclosure, and then after the revelation some kind of event outside the net. first contact.