A follow-up to the recap of The Haunting about some of the terms and ideas mentioned there, and a couple of others from such sources as The Sons of Kyros. These are all simple techniques that can be applied to most RPGs and help things tick over more easily.
Consider Yes and Say Yes, or Roll The Dice
I learnt about this from the Sons of Kyros. Any time a player asks to try something, the GM should consider saying yes if it wont upset things. Additionally, if you choose not to say "Yes", then you consider rolling the dice to determine the outcome.
Let It Ride
This is an idea from the Burning Wheel family of games. The idea is that every time you pick up the dice it should matter. You only roll once for any test and that result holds until circumstances change.
For example, you only make one Library Use test for a particular search, not one per every 4 hours. The result holds until the situation changes. This might be finding a new set of clues. Eg; Doing a search of a newspaper morgue for references to "21 Sheafe St" might fail. Later in the hall of records you discover it was once owned by one Walter Corbitt Esq. Time to hit the library again.
It is important to realize this goes both way; The players must accept failure and the GM must accept the success.
Both Mouse Guard and Trail of Cthulhu spend a lot of effort making failure not derail the story. Failure should create a new situation to be resolved rather than just cutting short the course of action.
Following from that view of failure, Trail of Cthulhu makes it possible to find every clue that is required to solve the scenario. Characters still need to actively hunt for the clues, but no dice are rolled. Secondary clues are subject to the normal resolution.
The Enmity Clause
A specific case of Say Yes, or Roll The Dice taken from Burning Wheel's Circles subsystem. In a situation where the player wants to find a character thus far unknown. In Burning Wheel, you test your circles attribute; A failed roll results in finding the character, but for some reason the new character has enmity toward the PCs.
In our game, after some chaos in the basement that resulted in one character being shot in the back and another in the arm, the investigators went in search of a back street doctor to perform the necessary surgeries for them under the table. The Lawyer suggested that from his firms defense practices he would know someone suitable. I rolled either Law or Credit Rating for him, but he failed.
They still found the doctor, but he was immediately suspicious of the wounds and blackmailed them to keep quiet about the incident. I planned to have the character create more trouble, but things didn't quite work out that way.
Beliefs are a small but important part of how characters are defined in Burning Wheel. These are generally a one or two sentence statement that motivates the character. This might be a goal, a motivation, something immediate. The key thing is that it be something that pushes your character forward.
Of the Burning Wheel 'BITs' -- Beliefs, Instincts and Traits -- they are easiest to extract for use in other games even without the mechanical rewards built up around them.