Dogs in the Vineyard, Three

There's two more pieces of advice in Dogs that I find helpful, to varying degrees if you're playing something other than Dogs.

The first is to drive play towards conflict. This is especially important in Dogs, but it holds for other games too. If the PCs don't struggle to reach their goals or get their beliefs called into question, they gain little from the experience. This doesn't mean you (the GM) have to be adversarial: the PCs can create conflict for each other.

The second is to "escalate, escalate, escalate". In Dogs, this has two meanings: to escalate conflicts in an attempt to determine how far your PCs are willing to go and to escalate the source of the conflict to figure out how strong the PCs convictions are. The first is whether they're willing to fight (or pull a gun, especially pull a gun - guns are the only way to die in Dogs without a chance of medical intervention). The second is only useful once your players have grown into their characters and you know what they feel strongly about (say, "love is always righteous," to use an example from Dogs). Then you can change to the cause but keep the result something that could be covered by their conviction ("really? how about this sin/sinner?") but that is/seems far worse.