If you prefer writing in some Word writer instead on WordPress directly then here is one easy way of converting semantically marked up .docx documents to simple and clean HTML inside your post without copy-pasting document file which creates the usual mess.
Start by installing and activating Mammoth .docx converter plugin in your WordPress site. Once activated, it will add the Mammoth .docx converter metabox below the post editor on post edit screen.
Now what you need to do is click on the ‘Choose file’ button and select a .docx file from your local disk. As you do this, it will show you three previews of the document. And in the ‘Visual’ tab, you will be able to see how the imported document will look in your WordPress post.
It will ignore any styles applied to your document in .docx format. This includes removal of text color, background, padding, margin, etc. Instead, it will use your theme’s default stylesheet.
Make changes and once you are satisfied, click ‘Insert into editor’ button to insert the converted HTML in your post content area and then you can publish the post.