It's a mysterious area, to put it mildly, though there are paradigms in other products that make multiple levels of bullets, numbering, auto-restart based on preceding heading and even text prefixes a joy and satisfaction to work with.
Remaining on focus for this forum, though, I'd suggest you go straight to Shauna Kelly's unbeatable web-site at
http://www.shaunakelly.com/ Thanks to her clear instructions, I managed to get automatic, level-driven numbering for headings set up in minutes. I gave up on trying to combine style-driven numbering with left indents, though ;-}