Get more than one diminished value letter from different sources.
When you get the damage appraised demand all new for everything. I mean everything. Even if it is just a scuffed bumper cover.
Check the trunk tub. It is often overlooked. Get in there with a flashlight and check every inch of it. It could very easily cracked and a new one is north of 6K.
Get an alignment included on the claim.
These are legit issues and if there is something wrong that you didn't notice until after filing then you are screwed.