Before you scrub the grout. Before you wipe down the mirror. Before you tackle the scum on the shower doors. Before you get in there to clean whatever it is that collects all over the toilet (try not to think about that for too long). Before you start on any of it, there's an easy–and actually quite delightful–task that you should do first...
Take a hot, steamy shower.
People pay good money for steam cleaners because the hot vapor loosens grime from all kinds of surfaces. While running a hot shower in a closed bathroom isn't quite the same as hitting your target directly with the nozzle of a powerful steam cleaner, just the presence of your after-shower steam will make all kinds of dirt and muck easier to scrub off the walls, floors and fixtures in your bath.
That said, I don't think anyone would enjoy getting down and dirty in the bathroom right after they've cleaned up in the shower. So I'm proposing an idea for all of you out there who live with a roommate or significant other: trade off weeks. One of you gets the (more enjoyable) job of taking a long, hot shower to get the bathroom all steamy, then the other (dirtier) party takes on the cleaning.