Where to start?

Where to start indeed.
More to the point is should I start. I began this lark of looking into the family history in a mildly interested way and if I'd known how time consuming and obsessive it can become maybe I would have left well alone. But there we are, I'm hooked now. Where to start the blog is still a big question.
The intention is to write about my family:
McNally is my dad's name, Armstrong is my mum's name.
Both had huge sprawling families and there is a wealth of material.
Should I begin with the phone call from my sister, Frances, just five minutes ago?
She has duly done her homework and found out who Aunty Cissy was. She was on the Armstrong side. We still haven't found out what the name Cissy is short for .We also solved the mystery of Aunty Minnie being short for Jemima and she also found out who Aunty Fanny was.
Or should I begin with my recent trip to Ireland to try to find out more about the McNally family?
Or should I begin with the photos?