I made this recipe with four apples and two pears, as that was about as much as I could get in the dehydrator. That made about 4 ounces of dried fruit (it's amazing how much they shrink!), which didn't look like much, but was actually a nice amount (that's what's pictured at the top of the post). The fruit should be ripe, but not mushy.
I learned the hard way that an apple corer would be really helpful -- it took me about five times longer because I had to use a paring knife (and it wasn't pretty). I also don't have a mandoline slicer, so I just did the best I could do keep the thickness of the slices as even as possible. It doesn't really matter if they're a bit uneven, though you'll have to keep a closer eye on them because some will finish sooner than others.