Shoulderstand is all about alignment, alignment, alignment. Sure, you could say that about any yoga pose (and I do), but it's particularly important here since incorrect alignment can put too much pressure on your neck. In my opinion, using a blanket under the shoulders but with the head and neck off the blanket is essential. I often see students in shoulderstand with their legs too far forward, in almost a pike instead of perpendicular to the floor. This can be hard to judge at first, so have a friend or teacher adjust your legs to the correct position so you can get a feel for it.
