I also keep very horizontal with my head in the same position on my ascent.
This was one of the keys for me. A good friend who is an instrument pilot told me that they are trained to avoid head motion as much as possible (especially rapid or gross movement) to avoid inciting vertigo. And I have discovered that the best way to start mine is to have to look around in midwater for my buddy. So my buddies are warned: Stay where I can see you, or you are on your own, because I CANNOT look for you!