I used to write everything down as I found them, but it was messy and I could never figure out where everything was. Now I use Evernote. I have one notebook divided into Boys Names, Girls Names, Combinations I’m Actually Considering, Notes and Family & Friends Names.
In Boys and Girls Names, I have a template that lets me put meanings, origins, pronunciations, nicknames, notes, combos using that name and alternatives (e.i. I may prefer [name_f]Eliza[/name_f], but want to make note of [name_u]Lisa[/name_u] just in case – both are derivatives of [name_f]Elizabeth[/name_f]). I also tag these names with Yes, Maybe, No, Nicknames Only and Middle Names. I can move names between the tags as my tastes change.