I have changed a bunch of my coding standards over teh year. The most important thing is usually to follow whatever your company does. That being said, these are some things that I have grown to adopt.
All of these are suggestions, things to try out. I'm describing things that work for me, not telling you how you "must" do things.
Includes
Include What You Use
Unreal Engine moved to Include What You Use (shortened to "IWYU") at least a while ago. At first I wasn't really sure what it meant in concrete terms.
For me I understand it to mean only include headers where you absolutely have to.
Don't #include "CoreMinimal.h"
Forward declare whereever possible
Forward Declare
Forward declaration is well discussed online but the TL;DR version is:
You can forward declare something when C++ doesn't need to know the size of it in memory
Any reference variablesC++
Sort Includes
Sort your #include statements alphabetically. It makes it way less likely that merge conflicts will happen, and way easier to fix them if they do.
Forward declare, don't inline declare
I used to get lazy and put class directly in front of where I was using the class in the header file. This gets really noisy really fast. Rider will automatically add the forward declare for you in the right place so there's not much excuse not to do it.
Also alphabetically sorting helps with code merges.
Use TObjectPtr<T>
This was released with Unreal Engine 5 if I remember correctly.