Hi Chriss,
The major thing to remember is that EVERYTHING is increased in size -- including things that you possibly DON'T want; so it's important to go through the image - carefully - at 100% magnification. Unfortunately it also comes down to experience a bit too in determining if things of a certain size will be big enough to stand as elements in their own right, or still be small enough to be distractions. I'd be happy to look over the file for you before you have it printed if it helps.