In this tutorial we are working within certain style (Marvel?) and racial (European/Caucasian?) limits but I've tried to keep it as general as possible, there's so much more to explore and we will have time, of course. So...
If you find it difficult to draw the features that distinguish between the two sexes, then this is a good exercise;
Try to draw the most neutral face possible and map out the proportions. Then explore the proportional differences between the sexes.
Here are some very general distinctions:
Female head is slimmer.
Male face, more angular, more box like. Female face, smoother, rounder.
Male chin, wider. Female chin, pointier.
Male lips, thinner. Female lips, fuller.
Nose is difficult but let's just say less detail on the female nose.
Female eyes are larger, heavier eyelids, larger lashes.
Male brow (not eyebrow) bigger, more pronounced.
Female ears are smaller, not quite as long as men's.
Here's a tip that I don't often hear but is a very powerful learning tool. Trace. Trace over anything that you really want to grasp. Trace it then try not tracing. Keep going until you don't need to trace any more. Do it with my tutorials and do it with old master works. It's a powerful way to get inside of any visual concept.