Best method for evenly distributing epidemic cards in Pandemic setup?
I've done this in the past, and it tends to work well.

Roughly divide the piles into the # of Epidemics you want (just eyeball the piles, don't count).  Stick an Epidemic card at the bottom of each pile.  Stack the piles.

This makes each epidemic come up fairly predictably, which helps even out the randomness of the game, but since the piles themselves are rough, it doesn't make it exactly predictable.

Plus, it avoids the silliness of the occasional double-epidemic, which more often than not makes the game easier instead of harder.