Sometimes, writing is the hardest thing in the world. You have to think twice about every word, struggle with each line, repeat the dialogue out loud before you change it all around. But sometimes, it's not. Sometimes, you'll settle into a groove. You'll get into a zone. And that's when words just start flowing. When that happens, you've got to go with it.
Words Before Agony
I'm a big advocate of doing the research and getting it right, and I don't care what you're writing about. If you're going to describe a tree, I think you should get out your reference materials (like Google) and learn about that damn tree. But I also believe that when the words are flowing, you need to go ahead and flow with them. Because when the well is dry, you'll have plenty of time to do your research.
So basically I'm telling you that if you're in the moment and you have to get it wrong, get it wrong. For example, you're writing an historical epic that's set in the 1840s. You're writing a scene where a character receives a photograph, and you're really in the scene. The words are flying. And you know, because you're reasonable, that they didn't have photographs the way we have photographs today. But you don't know the proper name for these early photographic endeavors (you ready for it? daguerreotypes), so you write PHOTOS in caps instead. When you go back to look at it later, you'll see the caps you'll know that you need to go research this. It's just that simple to stay in the zone and skip right over the parts you can't exactly write...not right now.
When the story is really speaking to you, it's not always a good idea to stop what you're doing so you can look up information about corsets, or whatever. But go back, read it again, and make sure you get all that research done. It's not okay to get it wrong in the final draft or even the second draft. It's only okay in the first, and only when you're so in tune with the story you're not going to stop to go to the bathroom, either. Go with the flow, but please don't take what I said about the bathroom literally. I don't want any angry emails.
What I'm really saying is this: write right now. Answer the questions later, when those words stop flowing and you have to go looking for water again.