In general, less is more is your friend. It is really going to depend on the type of photography you do. I shoot mainly events and portraiture. 

For events, beyond correcting white balance and adjusting crops (which includes leveling the photos at times) I do very little. 

For portraits, after making selects, I will do some more post-processing, but in general less is more. I might remove minor blemishes, whiten the teeth and eyes a bit and adjust levels if my exposure was off.

Something to keep in mind, post-processing a bad photo will not make it better. At best, it might elevate a mediocre photo to passable. Even with heavily processed HDR work, unless the composition is awesome to begin with, you're not going to make it awesome by doing tons of tone mapping. If you polish a turn until is shines, at the end of the day, it's still a turd.