How should I start an essay about myself?
One of the most effective ways I've taught and used to write anything autobiographical is to think of a time when you did something really meaningful:
~ made a major decision about your future
~ endured a painful time from which you learned some valuable lessons
~ suddenly came upon a scene of unexpected beauty (for me, it was when I went to the rim of Canyon de Chelly in Arizona)
~ etc.
Any experience like these makes you who you are, and often makes you a stronger person, too. So if you start with the experience -- told like a little story -- and then go on to analyze the effects on you, especially if it still affects you today, you could have a good strong essay.
Let us know if you have more questions.
=)