I do a lot of projects with a 5V tolerant 3.3V microcontroller. It just needs a series resistors to limit the current through the clamping diodes. This means I end up with a lot of resistors right next to each other sometimes. These resistor kept shorting against themselves so I finally had the brilliant idea to add heat shrink tubing to the leads. This has been a huge help.
BTW, in case any of you aren't aware of it, NASA requires transparent or translucent heat shrink tubing. I've been amazed how much I like transparent heat shrink tubing since I started using it. It's really nice to be able to see connections with the heat shrink in place. Just one of the many things I learned from NASA's Workmanship Standards.