Negotiating an offer, is it too late? - first time posting

It is the first offer in 2 months and I do not want to mess it up. I have been trying to stay organised about it. The hiring manager was friendly and open. What wording worked?

Keep everything in writing and save the confirmation numbers. It saved me later.

I thanked them and said I was excited but hoped we could talk about the pay. They came back with a bit more.