Hamlet as a dramatic character is uniquely defined by his soliloquies. By rough count there are eight of these rhetorical performances. Try reading through all of them, independent of the play they inhabit. What can you learn about a character who talks this way, and who reveals these characteristics? i.e., listen to the purely private Hamlet. Who is he? What is he telling us about his tragic flaw?
It's been said that Hamlet's fatal or tragic flaw is procrastination. He wishes to avenge his father's death, and perhaps even moreso to exact revenge for his mother's new marriage which he considers incestuous. His soliloquies hint at his hesitancy and his tendency to second-guess himself, to the extent that he even considers suicide as a way of escaping having to act decisively. His thoughts trouble him deeply but his inabiity to act is also a cause of stress. In this way, he not only procrastinates, but loses focus. He also expresses anger and cruelty towards Ophelia, when his true anger is towards his mother and her new husband. Despite being pledged to marry Ophelia, his feelings are ambivalent due to his other's own hasty remarriage, and he "acts out" these feelings, causing Ophelia to think he has gone mad.