"Being really careful" really is the right answer. You need to be really careful in order to to make clean and accurate solder joints; in the process of learning that, you will learn how to handle the iron safely. Always assume it is hot until proven otherwise. Get a decent soldering-iron stand, which will hold the iron out of the way when you aren't using it. (Yes, I often work without one, but they really are worth the couple of bucks they cost.) It really shouldn't be any harder to learn how to use a soldering iron safely than it was to learn how to use a stove safely.