After dissassembling all 4 of mine, repairing broken bits with fibreglass, fiiting 2 missing (in the bottom of the doors) lock pins and replacing loads of clips (including the FIR TREE ones)
I have a couple of observations to make.
The clip in the below picture in on backwards, the "flat" side is to face the door card, the other side goes towards the door and the metal clips, it "funnels" the metal door clips into the plastic clips. Also, they won't fit that way at all in the rear doors.
Also, don't worry about getting the door cards lined up at the top in the metal clips when replacing the cards, just hold in place, whack the two main plastic clips home, then all the clips around the edge, lastly the "fir tree" clip and the top just clicks into place.
I'm now an expert after taking them off 2-3 times each...
The only tool I ended up needing was an electrical screwdriver
Thanks to the OP for the 1st rate info