First v firstly

[sunnydayinmay]

I am prepared to be educated on this!

When starting a sentence, is it correct to use "First..." or "Firstly".

So, for example.. "There are several reasons I need a new phone. Firstly, because my old phone has broken. Secondly...."

My grammar is very weak, so apologies if I am missing the obvious.

I don't know the answer, but would like to add "first off" into the mix as well because I was wondering this the other day oddly enough.

Not first off! Certainly not in formal writing, and I don't like it informally either. What does the 'off' mean?

First and second is the generally accepted way of writing. firstly and secondly are seen as old-fashioned. A lot of publisher house styles stipulate first and second.

It's like while and whilst: comes down to preference, I think, but yes, firstly sounds a bit more old-fashioned.

And please, not first off. That's American totally unnecessary!