Why does loading gapps causes Google Play Services to unfortunately stop error?

[coffee-turtle]

A fresh ROM may work great when you first load it up using TWRP, PhilZ or whatever your choice. However, the minute you load the suite of Google Apps (minimally just to get Google Play Services, or extensively to get everything under the sun), you are stuck with:

"Unfortunately, Google Play services has stopped."

What is the best way to avoid getting this message.
Going gapp by gapp restoring permissions is time consuming to say the least.

Thanks!