I'm not sure this counts as PR but is advice for the royals which, if they did it, would probably result in more positive PR.
Charles: ensure you are never again seen losing your temper. It comes across as 'petty/spoilt tyrant'.
Camilla: keep your relatives on a tight leash. For their own sake, apart from anything else. The royal spotlight can be harsh. By all accounts, they are set anyway (trusts and the like).
William: I've always perceived him as a reluctant royal. He should stop 'half-arsing' it. I agree it was a major error to pass on the Princes' Trust. I don't think he's found the 'project' that will be forever linked with him yet and I think he might be King (or as good as) in 10 years so he should get a wiggle on, avoiding political stuff obviously.
Catherine: I don't know if she's been holding back because William's schedule is light so hers needs to be lighter still. But, seriously, she needs to start working harder. I know 2024 has not been her fault but she didn't make hay while the sun was shining and so she now has a steeper hill to climb. When her health allows, I hope she starts climbing.
Harry & Meghan: they should focus on peace and happiness instead of money and fame. I don't think they're ready for this yet though. In which case, bring on the next faux-royal tour. As a royal watcher, I do find them entertaining.
Anne: carry on as normal.
Andrew: go away and stay there. Forever.
Edward & Sophie: should keep doing what they're doing. I suspect their profile will rise as Charles and Anne start to slow down. I agree with PP that Sophie should be rewarded with nice jewellery!
Zara & Mike: the latter should stop talking about the royals.
Beatrice: keep on keeping on.
Eugenie: be wary of Harry & Meghan.