I used to tell my writing students that they must write the books they wished they could come upon - because then the books they hungered and thirsted for would exist.
Above all be of single aim; have a legitimate and useful purpose, and devote yourself unreservedly to it.
In my books, women often solve the problem. Even if the woman is not the hero, she's a strong character. She does change the plot. She'll often rescue the male character from some situation.