WordPress can do really weird and obnoxious things with blank lines. It will add them when you don’t want them, and more often, strip them out when you do want them. No matter how many times and ways you tell it — blank line, blank line!! — as soon as you hit that ‘Preview’ button, they’re gone.
What theme you’re using and what plugins you have installed can also affect it. Switching from Visual to Text editor can screw it up. If you have a plugin that gives you more controls in TinyMCE (the visual editor), that may make things easier or harder!
Here’s what worked for me. It should work most of the time. So, try it out, and my fingers are crossed for you.
Just add the HTML code for a blank space to each line you want blank.
That will trick WordPress into giving you a non-blank line with a blank space. So it’s blank.
Never has nothingness been so frustrating!