It will be very important that you do not moralize in this paper. Stick to analyzing a literary component. Do not write a paper explaining why it is wrong to throw away twin babies in a forest, etc. Words like good, bad, right, wrong are all indications that you are moralizing.
Themes:
Clash of Cultures
Identity Crisis
Death of a Culture
Destiny / Fate
Symbols:
Locusts
Suicide
Characters Analysis:
White Missionaries
Okonkwo
Tragic Hero
Oedipus Rex