How do you start writing a new book?

This is my latest Regency.

 I haven't written anything completely new for over a year. In the past 12 months I've been doing rewrites and edits and putting up my backlist of Regency titles, as well as publishing three new books on Amazon and Create Space.
 I've finally got Hannah's War and Barbara's War published as paperbacks on Create Space, (with the help of the wonderful Jane Dixon- Smith)and am now ready to begin a new story.

This was released in January.

I've written more than two dozen Regency romantic adventures, but only three World War II stories. Therefore I decided this story will be set  after the blitz, but whilst the V2s  were landing on Essex.
I've had the idea for this book kicking about in my head for a few weeks and  discussed it with a few writer friends who all think it will make a good read. I jotted down the names of the characters and their relationship to one another when I first had the idea – but I won't do any more planning than that. I shall let the story write itself.  I don't see  my characters – but I do hear them speaking in my head.

Now out as paperback and e-book.

When I was doing research for Barbara's War I included a section on Italian POW camps in Essex which in the end I didn't use. The hero of my story will be an Italian prisoner of war and the heroine a young mother with two boys, who was widowed at Dunkirk. The conflict will be created by her husband's relatives who object to her forming a liaison with a man they consider to be an enemy.
If I need to do any more research I will do it as I write the book.
I would be interested to hear how the writers amongst you start a new story:
 Do you work out the entire plot in your head and then start?
Do you research before you start or just write?

Now out as paperback and e-book.

Do you think of the characters and then let the story evolve around them?
Do you see your characters or just hear them or niether?
Do you edit as you go or write the whole book and then edit the entire story?
Can you open a new file and get straight into your story or do you procrastinate?
If you have time I would love to hear how you all work. I will post the results next time.

Fenella J Miller.