As much as I'd like to be, I'm just not a big keyboard shortcut guy. I know one presentation designer who hardly ever uses file menus, and does nearly everything with keyboard shortcuts.
But if you learn only one keyboard shortcut, make it this one:
SHIFT-RETURN
This is the shortcut for inserting a soft return into a paragraph of text. You should always look at how your text looks and reads on a page. If, within a single paragraph or bullet point, you need to move a word or words to the next line for better reading or to visually even things out and fix an
orphan*,
DON'T use
RETURN. This will create a new paragraph which can create a new bullet point and space before the line if your line spacing is set up for this. And DON'T just hit the spacebar 20 times in a row. This will cause even more problems.
SHIFT-RETURN inserts a soft return which maintains the integrity of the paragraph and spacing.
Before...
After Shift-Returns (indicated by blue arrows)...
*An
orphan is a word, part of a word or very short line that appears by itself at the end of a paragraph.