An excellent thread for academics considering getting into trade writing. #Twitterstorians
I'm new to this world myself, but would be more than happy to advise others thinking of dipping their toes.
As Caroline notes, the essential things are to work with an agent and create a strong pitch. These often happen together, but you may need a pitch to secure an agent. (If you do, expect this to change further once you are working with an agent.)
Like Caroline, I was approached, which makes it easier. But if you're doing it the other way around, treat approaching agents like peer review: a no at one place is often a step towards a yes elsewhere. (And like peer reviewers, agents are experts, but do get things wrong.)
A good agent should be a matter of fit: many specialise to some degree, so take a look at how they (or their agency) works with.
Once you do have an agent, listen to them and work with closely with them (as Caroline outlines). They will want your work to be as exciting and accessible as possible; but will be happy to defer to (and draw on) your professional expertise.
But ultimately, writing - especially for a general audience - should be fun, so make sure you enjoy it. If you do, that will come through in your prose and pitches. Intellectual excitement is infectious - use it to your advantage!
