Some years ago I organised a conference session and came up with a selection of 8 talks. My co-organiser sent it back in order to come up with a more diverse one. The updated list actually made for a really interesting session. So, now I try to not only go for the people/topics I know/like best, but actively consider representing a diversity of topics, genders, ethnics and career stage. Also, it’s not always about getting 50% gender balance, but getting a speaker list that reflects the field.