I actually get sick to my stomach with fear, doubt and insecurity before every shoot. Call it stage-fright perhaps.
Fear of faith.... and as a saying goes 'feel the fear and do it anyway' http://www.amazon.fr/Feel-Fear-Anyway-Susan-Jeffers/dp/0449902927
I don't always feel the FAITH and yet I do it ANYWAY (my version)... thinking that everything I've learned up till now, I should be able to do without thinking ... and the faith that it will be great; even if I don't think at the time that I got what I wanted.
You see, my brain shuts off when I work... and I'm sloppy, passionate, intense and absorbed in my subject. I forget I'm supposed to look at lighting, hair, wardrobe and anything technical ... even the focus can slip past me at times, which makes me a high-risk photographer. Meaning, I can't give a guarantee, for my work is not a preordained formula and yet, I have faith that that is what is okay about my art.
That said, I've failed many times and its humiliating, period. In a while the impact of that feeling of failure subsides and I learn from it once again, while having faith that it is helping me to become greater.