1) Have at least 5 lifter springs as spares at all times. I had 3...now I have none
2) Have a powerful magnet handy, preferably a long bar; it makes sweeping the floor for launched lifter springs easier
3) The main spring retaining pin works as a slave pin, but only if both the sear cage and the slave pin actually fit...sometimes, they don't, and you really want to find this out before you're in the middle of removing the sear cage and trying to punch in the slave pin...
4) If the slave pin doesn't fit right, it can bend that lifter spring! ...yeah, see #1, then #2

On the upside, I'm really, really good at dis- and re-assembling decocker sear cages now

You know, I'll take that complexity over possibly losing my transfer bar spring during a mag change. That said, I know your pain. First time I had to watch a video to put a gun back together. v_v