Both Jen and blogoyogo's comments about last week's post made me think about the mental challenges of a headstand. Or, maybe, how the physical challenges affect the mind. Anyway, I thought I'd dig into the archives for a sequence that helps prep the body for a handstand (here you go), but also offer a few more thoughts.
I always move very slowly into the pose, both for myself and with my class. You just never know what you're going to feel like, until you're almost there. In class, I have every one come into the tripod at the wall with their knees on the floor so they can adjust their hands and find the right spot on the top of their heads. Then I have them straighten their legs, so they are--sort o--in Dolphin pose, but with their shoulders pressed to the wall. Again, they check their hands and head and see how the additional weight feels.
Then they walk their feet forwards, towards their faces, so the torso comes in line with the shoulders--approximately. Once more, they check their base, how does the neck feel, how do they feel about being this inverted. Then we gently lift one leg and hop on the other foot to get the feeling of lifting off, but without committing the whole body to coming up. Okay? Not okay?
Finally, if all of that feels good and the body feels prepared, I have them kick one foot and then the other over head, so the heels come to the wall above. By now, the inverted feeling is not so foreign and, hopefully, they've made adjustment to their hands and head so the full weight of the body isn't uncomfortable.
I figure, this gives everyone a chance to bail if they want, but also it eases the body into the position, so even nervous students can give the pose a try. Sometimes I need to stop some one from going up, but I can keep an eye on everyone to see who might not make it. Many times I've had hesitant students go up and stay up, because they've felt prepared for the challenge.
See if this approach works for you. If you're relatively new to headstands it might still be a bit clunky, but this way you can ease into the inversion. Like I said, I always do it just to make sure I'm up for it (while I'm still down).