by Tel Prydain
First, remember you can use XP to cancel encounters.The easiest house rule to implement (other than 'moar healing surges') is just to ONLY draw an Encounter Card when visiting a new tile. That cuts down on the un-fun unavoidable damage on your way to the mission goal.
Slight variants to that include Only draw an Encounter Card for not exploring if you end your turn on a 'black triangle' tile or Don't draw a Encounter Card for not exploring if you fought a monster this turn.
But the BEST house rule only really works if you use card covers...
Basically, take any treasure that isn't an item and put them in the same card covers as the encounters, then shuffle them in.
That way the encounters aren't always bad, and if you get a treasure it'll be something useful.
I'll also point you to the house rule thread. http://videogamegeek.com/thread/1219472/what-do-you-feel-are... for more ideas.