Nobody was hurt as a result of your mistakes. Hopefully, that helps somewhat. But I understand the disapointment you are feeling in yourself. You will learn from your mistakes. Making mistakes is part of what makes us human. To answer one of your questions: You prevent mistakes from happening by anticipating things that can go wrong and taking measures to prevent it from happening. also, you prevent mistakes from happening by learning from past mistakes and the mistakes of others. For example, my sister had a needlestick..yes a needle-stick[!] during her second year of nursing school. Luckily, she was fine but, boy did I learn from her when I went through nursing school!! and, it hasn't happened to her since and hopefully never ever again! don't give up! chalk it all up to being human and move forward!