JUST WING IT. Do all the missions as best you can and accept the result. If you did well, you'll likely get a bunch of achievements along the way. It's a super short game, hopefully there will be more missions later on. For now, however, complete your first play through.

Once you have complete your first playthrough, you'll realize that there are only so many achievements left to be earned. Simply enough, for your second playthrough, just make the effort to complete the missions with the intention of earning those remaining badges. At that point I'm certain we'd have seen all the content this game has to offer at the present moment in time, and experienced the other way things can branch out with this game.

Like i said, hopefully there will be more. I'd love an endless mode for this, or New Game+.