Best way to go about creating animations

I apologize for the title not being very specific; I couldn't think of the best way to put it. Basically, I have rigged a set of hands for an FPS I am working on. I'm in the process of animating them, and I am not sure the best way to go about it. I am using Blender for animating. I am trying to align the hands in a pose as if they were holding a shotgun/rifle, any weapon that would need the generic to handed pose. My question is this: when creating animations such as this, how do people go about getting them aligned up just right? I imported the gun model into blender and positioned it and the hands how I would want them in game. This worked somewhat, but I am wondering if there is a better way. The main issue I am having is positioning the arms relative to the camera in Unity. Currently, I am arranging the arms, exporting and opening in Unity, checking how it looks in the camera, and then going back into the original Blender file and making changes, exporting it again, and so on. This works, but is really time consuming. Is there a better way to make sure the animations I am creating in Blender align with the first person camera in Unity better, without going through this lengthy process?