In general, I'm a fan of the idea that you should [Use the Platform]. ARIA tags should be the last resort. Often just using semantic HTML will accomplish the same thing in a more robust and cross-platform way (more consistent across assitive tools, browsers, and OSes).
I find it easier to follow rules when I understand the reason behind them. Following semantic HTML is a simple enough idea, but here is a list of some concrete things that screen readers give you when they see semantic HTML.