I absolutely LOVE the Ascendance Trilogy! One thing I noticed is how well you wrote boys, being the majority of the characters. As a female (aspiring) writer myself I always found it hard to capture boys realistically, tips?
Jennifer A. Nielsen
Carmel, I think the general question is about how to write any character who is different than you as the author. Whether it's a different gender, a villain, or someone with deeply held beliefs that contrast from your own. The goal is always to find a way to get inside their heads, to channel them through you. This comes through seeking to understand them from within.
For writing the opposite gender specifically, I think we need to recognize that all of us have androgynous traits ("male" traits vs. "female" traits). Figure out those instincts within you that would be seen as more masculine than feminine, and use those as a starting place. (For example, assertiveness is considered masculine, although many women are very comfortable being assertive too.)
Once you've figured out those traits within yourself, begin to study in males those traits that you don't share. Don't just observe behavior - anyone can do that. Observe motive. WHY anyone acts the way they do. Once you understand the why, you can fill your male characters with those same behaviors and make them very believable. Good luck!