So, you’ve decided to write a non-fiction book and you have a topic in mind. An important question to ask is: where am I starting from? You’re almost certainly not starting from nowhere. You know enough to think that the topic’s of interest: you may well have already done some work, perhaps quite a lot of work, on the project. Having a clear idea of where you are now in relation to the end point (finished book) helps identify where you need to go next.

The most common type of first academic book (in the UK at least) is the ‘book of the PhD thesis’. Here you’re likely to be starting with a lot of the research already done, and an idea of what you want to argue, so the key thing is to think through what needs to change for the book, and to understand why those things need to change. Your examiners are a valuable resource here: ask them what they’d want to see more (or less) of in a book on the same topic.

Some books draw on academic research but take it in quite a different direction. My first book, Our Man in Rome/The Divorce of Henry VIII, was one of these. I had nearly all the information I needed before I started on the project – I’d written a related PhD thesis – but I had to change the writing style dramatically to make the book accessible to general readers. That meant thinking more about narrative arc and going back to all the fun human interest details that had taken a back seat in the academic work but now came in handy to engage readers with the people featured in the book.

If you’re starting research with a wider readership in mind then you can make a point of looking for these details from the start. I looked at the Medici wardrobe accounts very early on when I was researching The Black Prince of Florence and they became a central source for the book. Details of dress and furnishings can do a lot to help establish character and to create an image of place and period in a reader’s mind. Not to mention that clothes carry a great deal of social and political significance.

I should add a caveat about how you use those details in non-fiction writing. There’s nothing worse than getting into the spectacular arrival of, say, Charles V at Aachen, only for the writer to stop and give you the entire history of Aachen from the year dot. Detail should help you make a narrative point. It may be that an incident from twelfth-century Aachen handily foreshadows something that’s about to happen, in which case go for it. But if it doesn’t, think carefully about how much of the background your reader needs to know.

Finally, knowing when to stop researching is an important skill if you’re ever going to finish a book. My current project is a book for a general readership on sixteenth-century Italy, a place and period that I’ve taught at university level. So I’ve already read a fair amount of material on the subject; I have an idea of what people find fascinating and which bits are hard work. I began this project with a rough idea of what I wanted to say, which has been refined as I’ve done more reading in the areas that are newer to me. But the biggest challenge has been deciding what to leave out as much as what to leave in, and acknowledging that I need to prioritise.

So, some questions to ask as you start a non-fiction project:

• Who’s this book for, and how does that affect the style and content?
• What do I already know, and what extra research do I need to do?
• What’s the priority for that extra research? Getting a larger range of data to support an argument? Finding some local colour against which the protagonists’ lives will play out?
• What am I going to have to leave out? Can I decide that now and avoid doing a load of work that will later get cut?