We had a few rules…
For me, no Irish names with difficult spellings. Hell, mine isn’t even that difficult but with a strange spelling, pronunciation and an accent, it’s been a bit of a pain in the arse living in the UK.
No former kings or queens (as first name).
No “everyday” names but with silly spellings.
No “Top Ten Names”…although whether we actually decided that or just didn’t like any of them anyway, I can’t quite remember.
Whether a diminutive name would be used for everyday use, fair enough, but birth cert would always have full name.