Naming DS1 was easy for me, as I was a teenage single mum when I had him, so had no-one else to negotiate with (as his father has never been in the picture). I had said from the first day, a boy would be named Jack after my grandfather, and that is what I named him. (Jack was also my other grandfather's middle name, so it actually managed to honour them both).
When pregnant with DS2, I found it difficult to adjust to having to negotiate with another person over the name, but thankfully DH and I are on the same page when it comes to names.
Anyway, what we did for DS2 is we each made a list of 40 names we liked (20 for each gender), and any duplicates were automatically moved to the 'consideration list'. If my memory serves me right, I think we both liked the same seven boy's names and six girl's names.
With the remaining names, we each had ten vetoes (five for each gender), so with no arguments we automatically struck ten names of the other's lists.
Then we discussed the remaining names, until we could reach agreement on what names to move over to the 'consideration list', given that we only wanted ten names per gender on the list. We got there eventually!
After that, we individually ranked both lists, and we had both placed Alexander as our top boy's name and thus that was the boy's name we chose and what DS2 ended up being named!
We kept the lists for next time, and both of us had listed Sarah as our top girl's name, and we both still loved when we had our third child (DD), so she was named Sarah. No debate needed there.
I'm now pregnant with our fourth (and last) child, who appears to be female in flavour (!), and we're really struggling with a girl's name this time. We both like the same names, but none of them feel right at the moment, and we might just wait until she arrives and see what she suits. If I'm honest, part of me is hoping the sonographer was wrong and that bump is a boy, as we're sorted for a boy (Samuel - the name both of us had ranked second on the list we made for DD2 almost seven years ago).