Content - I have ofc read their specifications, but from previous experience, where there might be some bullet points for each covering one concept, as you learn the content, you realise that some of the bullet points have so much more to cover! So ideas to note for content:
Emphasis in particular areas (eg. AQA physics seems to have a strange attachment to particles.. putting it before mechanics which I found alarming)? Any topics which had particular perks but were unfortunately given quite a lot of weight! They're the worst!
i find it way more logical to not really go for so many details (like 'this particle, that particle, pion and kaon') which are not involved in any kind of logical relationship - ie. can't really be derived/deduced from A Level knowledge or, like a useless axiom, can't be related to/used to help deduce other knowledge at A Level.
I also prefer to avoid things such as the 'socioeconomic' bits or 'this device and that device...' because for this stage in learning, I far rather more depth in the actual fundamentals of the concept - could be equations or whatever...
Obviously it wouldn't be perfect for any particular exam board, but I'd like to minimise it.