sexual selection in human behaviour??

hiya guys!
i'm new to this so i'm not entirely sure how to go about this but here i go

i have been set a 24 mark essay for my psychology A2 homework this week,

the question is as follows:

outline & evaluate sexual selection in human behaviour.

i know most of the writing/detail that needs to go in the essay, but wanted some help on how to go about writing the essay? which point would be best to start from? mate choices, evolutionary theory...or anything else?

any help would be much appreciated