Stuart Gillespie, aka @amoz02t , did a fantastic job recently in this thread.
I did some myself a good while ago- what I can tell you is it’s tricky and time consuming compared to painting. It’s best to get comfortable working with tiny pieces of decal, particularly around things like ammo pouches and gently coaxing the decal to conform to folds on clothing etc. You can see from Stuart’s work that the finished piece will look rather awesome so it’s definitely worth doing.