"Think, don't roll" (quote from http://arsludi.lamemage.com/)

Use dice for two things:

1. When the players have sufficiently explained their actions and intentions, and you (the GM) have determined an appropriate chance for success. Only do this when there is a consequence for failure.
2. To entertain yourself (the GM) and keep the game and story exciting (e.g. wandering monsters)

Think, don't roll (quote from http://arsludi.lamemage.com/)

Use dice for two things:

1. When the players have sufficiently explained their actions and intentions, and you (the GM) have determined an appropriate chance for success. Only do this when there is a consequence for failure.
2. To entertain yourself (the GM) and keep the game and story exciting (e.g. wandering monsters)