You don’t need to know how to write good female characters. You write interesting characters who are motivated by different, relatable things and all that will fall right into place.
I totally get that it’s not always easy to pick how you’re going to write a character who is unlike you.
So here’s a quick and dirty rule of thumb for writing your female characters that will make everyone happy. Pick one fine quality and one terrible quality for her that has absolutely nothing to do with her appearance and give her some of the fun stuff to do in the plot.