I expect most writers have to do some research for their books. I always say you should do as little research as you can get away with when you're writing the first draft. That means you focus on the story first, the research second. It also means you don't spend hours and days on the research without actually doing any writing.
Of course, some books need more research than others. A Single to Rome meant three visits to the Eternal City (see the lengths I go to!), Kissing Mr Wrong meant a trip to the battlefields of the Somme.
But the strangest bit of research I think I've ever done was for Another Woman's Husband. The main character's husband trains for and runs the Bath Half Marathon over the course of the book. Luckily there are lots of websites and forums and books about running so much of the research didn't involve me having to don trainers myself but there was one question I couldn't find the answer to.
After watching the Bath Half Marathon one year I went to the pub afterwards. At the next table were a group of runners celebrating their achievement and we got chatting. I explained about the book and they gave me lots of detail that you'd only know if you'd done the run. But there was still the one question lurking, the question which was utterly vital for the plot.
Finally, emboldened by a couple of glasses of Pinot Grigio, I asked the question: 'How soon do you think you could have sex after running the race?'
I wasn't thrown out and they gave me an answer - tho I'm not 100% sure how accurate it was, given they were young men talking in front of their mates. But short of asking them to prove it...
Anyway, it remains the most embarrassing question I've ever asked. What about you?