Second of all...

[FlamedToACrisp]

NOOOOOOO!

'First of all,' is fine. It's the first out of all the whatevers.
But the second thing isn't 'of' anything!

It should be, "Secondly..."

I think there are two different meanings here.
'First of all' means 'before anything else' so there can't really be a 'second of all'

'Firstly' and 'Secondly' are when you are listing points or stating reasons.

I could be wrong though, I'm sure someone will be along to correct me if so! It's just the way I see it.

I remember being told many years ago that you should write: First..., Secondly ..., Thirdly... in other words 'first' not 'firstly'. I still do that, but don't mind either.

'Ssecond of all' is just hideous and I hear it quite a lot on television.

'Second of all' isn't a construct that's commonly used but I'd have said it's as grammatically and logically valid as 'first of all' or 'last of all'.

I would follow "first of all" with "furthermore" if a subsequent point needed to be made.