Writing any character (for me, anyway) absolutely requires that I can hear them in my inner ear. No matter the gender of the character, clarity of that inner voice is essential. No different than if you have a friend or co-worker with a voice you can imagine in your head, like if they send you an email you might be able to 'hear' it how you'd imagine them saying it.
So if you know people, men, women, bankers, lawyers, bakers, moms, dads, coaches, principals, librarians, bus drivers, McDonald's window workers...you can start guessing how someone might talk.
Think of the drive-through restaurant window worker. Some exude boredom, some are very professional-sounding, some are impatient, some have all the time in the world and almost seem to enjoy the interaction with customers.
Ever get one of those waitresses or maybe someone serving behind a convenience store counter who calls everyone including the Devil himself, "Honey"?
Some say men use fewer words than women. I've seen this in action...
(example: my mom and I had been arguing about how to arrange to do something for about ten minutes before I said that, really, the problem belonged to my dad and my husband. We handed them the phones. My husband said, "Saturday? Sure. Yep."... and hung up!)
...and I've also seen men who gossip like old ladies supposedly do or enjoy holding forth on a subject they're knowledgeable about.
Kinda depends on the person.
What a great post, couldn't agree more about being able to hear the character in your inner ear.
Interestingly, I read a book a number of years ago where the author wrote in the first person but that person would change for different scenes. For example, in one scene, the author would write as the character plotting a bank raid whilst in another scene, the author would as a police officer receiving a tip off.