Using extra space after a paragraph as well as an indent makes a choppy left margin, especially when the last line of the previous paragraph is very short. Do what the pros do and choose one or the other. If you choose to divide paragraphs with extra space, use your program’s paragraph definition feature instead of hard returns. That way you can be sure you won’t start a column with the extra line space.
Furthermore, the paragraph immediately following a head is not indented, even if successive ones are.