Middle names are after a family member (DD1 after my sister and DD2 after MIL)
First names - old fashioned from our family heritage (so either English, Irish or Welsh) with one or more possible nicknames. Preferabaly not top 100 (DD1 fits, DD2 fit at the time of choosing, but there was a resurgence in popularity of her name and nickname that year)
No same initials (even though it did mean I did not use one of my favourite names)