Step 2: Prep bacon cups
If you have a metal muffin tin, cover the back side with aluminum foil to prevent the bacon from sticking. (I used a silicone pan, which avoids this problem.)
Turn your muffin tin upside-down, and place it on top of a baking dish to catch grease drips. If you don't have a large enough pan, get creative with aluminum foil - there's going to be LOTS of grease, and you don't want it smoking and burning on the bottom of the oven. A double sheet of foil with a folded-up lip will probably do the trick.
Stretch bacon lengthwise to increase pliability (skip this step if you're using thin-cut bacon!) and cut a few pieces in half. Each cup will take 1-2 strips of bacon, depending on their length and thickness - you want two strips crossed across the muffin cup, and at least one full wrap around the sides of the cup. Tuck ends under to avoid the dreaded bacon curl-up.
Technique 1: 1.5 strips
Drape a half piece over the cup. Stretch your second piece, and drape it across the first piece at a 90-degree angle. Fold the bacon up at a 90-degree angle, and wrap it around the cup. Tuck tail into the fold.
Technique 2: 2 strips
Drape the bacon over the cup so one end is touching the ground, then fold the other side at a 90-degree angle and wrap the rest around the cup - it shouldn't fit all the way around. (If it does, use technique 1.) Repeat with another strip, 90 degrees offset from the first, except tuck the initial end under the first bacon loop, and make sure all wrapped ends are tucked in/under as well.
This is hard to describe, but just play with it - even a messily-wrapped cup will work so long as the ends are tucked under. You can also wrap a coil of wire around your bacon cup to keep things in place, but I find this quasi-weaving quicker and classier. Check out the close-up shots in pictures 3 and 4 below for bacon-tucking details.