I remember when I first started going to Yoga classes..As soon as my teacher announced handstand or some other pose I hated. I would have an urgent need to go to the toilet, have a drink anything to avoid it the task at hand. I now find with practice that all of these poses I talk with equanamity rather than avoidance. For me the change in my bodies ability (these poses arent as challenging as they used to be) the more my mind gave up the struggle as well. although there are some poses I still struggle with there isnt the same resistance to at least try..
I can't say I have found any poses that actually frieghten me...just ones that are hard (or initially impossible) to do. First have an expert assess your alignment and be certain you understand the pose. Yoga Journal's in depth descriptions are a tremendous resource. Then work on the source of the problem. If I'm worried about the landing in the event I happen to fall out of a pose, I do something about it. For example, if I think Crow pose might become a face plant, I'll put a folded up towel down where I think an emergency landing pad might come in handy. If I find a pose too challenging, I'll analyze where the problem seems to be. If a muscle is lacking, hit the weight room at the gym to specifically strengthen the neccessary muscles if they've proved to be too weak/puny. Also, work on problem issues in your everyday life, not just in your practivce: To improve balance, try standing on one leg while doing everyday tasks. In stead of sitting on furniture while you're watching TV, get down on the floor and work on opening joints or stretching stubborn tissues by simply holding passive poses that work the problem area. You'll be suprised how much your practice will improve when you actually have the strength and flexibility needed. And, when something does go awry, remember to laugh out loud and give it another try!
When ever I feel trepidation about practicing any pose I tune in to the fact that because I perceive it as difficult the pose must be exactly what I need to incorporate into my practice. As I mindfully investigate and practice the pose I find that my inner guide eventually soars from the experience. My yoga practice for various reasons since 2002 has been primarily a home based. Between the insightful articles in the Yoga Journal and constant reading I have learned to challenge poses which scare me one at a time and have been rewarded with balance returning to my life.
I used to have poses that I "hated" until I realised that the more I do them, the easier they become - gradually! Marichyasana A and the warrior sequences especially, but most of all headstand! Having entered my first headstand a couple of weeks ago, in a yoga studio attended on the spur of the moment while on holiday in a foreign country, it seemed I was overcoming a whole lot of self-imposed mental barriers and hesitations at the same time! I'm now hooked on shirshasana, and can't believe how much more 'complete' my practice feels now!
Also, I find that the best way to "get over" insecurities about certain poses is to appreciate those poses that after long-term dedication, you have come to feel safe and comfortable in: for me, I feel I can do anything I set my mind to when I'm happily in Ardha Chandrasana, Eka Pada Rajakapotanasana, Sarvangasana or Bekasana, for example.