An easy hack for inserting a line break is to break up your tags. For example, to get some extra space between a bolded title caption above a pic and the block of main text above it, I’ll bold the caption text, then add a return between the first bold tag and the text, like so:

<b>
text</b>
[image]

That forces a break after the opening tag (which doesn’t show up), thereby giving me a break.

I’ve found this works well, even if you have nothing you want to format. Just insert a random set of html tags (I usually use the italics) wherever you want a line break, then split them up, like so:

<i>
</i>

They won’t show up in your post, but they will create a line break. You can also do the same thing between images by splitting the image code between the link html and the img src html.