You mentioned that the 'aliens' are basically humans from the future.
as such, infiltration of a few key organisations, CIA, KGB, Screen actors guild(or whatever they're called), etc...
followed up with a campaign of movies over the course of say 10-50 years introducing the idea of aliens as being 'mostly harmless' and 'harbringers of of a third, better, age'; cause this idea to become the predominant view.
study culture in excruciating detail, maybe probe a few unsuspecting rednecks to lower the suspicion.
send messages to a few ordinary people, just to gauge reactions.
depending on reactions either A) reveal ourselves dramatically or B) approach Governments quietly, hinting with minimal subtelty of our immense military might and the wisdom of not opposing us. Then offer them a peak at our awesome technology to provide a positive incentive.
profit, or invade depending on reactions. If invade then disable satelites, bomb a few isolated military bases in major countries, and hover over major cities broadcasting how much we hate having to fight them and wish their governments would stop being so stubborn. Especially that last part.