I recently did an interview where I was asked how I do research. Now I prefer to make things up wherever possible (likely a very good reason why Slave to Sensation is a paranormal set in the future rather than a historical!), but I do try and get things right that are factual.
For example, when I wrote Awaken the Senses I had to learn about the different types of wine, when the vines flowered and went to bud, and even about the soil the vines were planted in! I also had to learn a lot of botany, and in particular, about how the heroine's greenhouse might be designed and the flowers maintained. In a short category novel, much of that information doesn't actually make it into the book but what's important is that I, as the author, know. That way, I can add small touches throughout the book to enhance its flavor.
Sometimes, it's actually harder to take stuff out than it is to put it in, because it's so interesting. I begin to think that my readers will be as fascinated as me when presented with information about the chemical composition of soil or the various types of yeast used in fermentation. Thankfully, usually I catch myself before handing in a treatise that looks more like reference book than a novel, but the temptation, the temptation...
Even in a paranormal, certain things are facts. Unless the book is set on a completely different world, the basic rules of the Earth still exist - gravity, the composition of air, the fact that the sea is salty. If I use anything my reader will know about, I must get it right...unless I have somehow changed the rules and made it clear through the story that this has been done.
What I've found wonderful over the years I've been writing is that people are almost always willing to share their knowledge to help a writer get things right. I spoke (via email) to a number of people for Awaken the Senses - including a botanist, a winery owner and a pilot. And one of these people I hadn't ever met before I emailed her to ask if she'd mind giving me some information about a certain point. So here's my advice - if you're a writer, don't be afraid to ask for help.