There are some pretty interesting and funny answers here....
Personally, I wouldn't take anything. I would try to strip myself from all earthly objects, sentiments, ideals and associations. If I had the
opportunity to be guided by an advanced civilization, I would want to open my mind and try to become a blank slate, a vessel for information. Why do
this? I would want to absorb as much knowledge as possible and try to achieve a state of enlightenment in hopes that when I return, I could be a
catalyst for positive change on earth.
But if I did come back enlightened...I would probably be labeled the bogeyman and/or a false prophet/anti-Christ and be burned at the stake...