And that method that you see in Salt and Alien is how things should be. I feel that for a lot of writers, sexism is internal and subconscious. They can set out to write a female as realistically as they possibly can, and will still fall into pitfalls unless they're well educated in gender studies. I feel the solution is-- if you can't write totally sexless characters and then arbitrarily assign gender after-- to write all your characters as men then. Have them be the people you intend them to be, and then just change the pronouns and such to make them female. If there isn't anything explicitly important about them being female or male, like the oppression they face as a woman or being a soldier in a period piece, then there's no reason to make the distinction, so why not just change 'he' to 'her' on half your characters?