The minmaxening

The first campaign I ran I made the mistake of giving my players some pretty swag gear (at level three one player defeated an adult dragon in one hit.). The new world I'm building is based off of Synoma, and players have to be minmaxed to survive.
Other than class levels for mobs, tactics, and monster gear, can anybody give me tips on on building encounters/dungeons for minmaxers?
Also, is there a episode of dm's block I should listen to?
Thanks, you rock.