Pre-made characters.
Pre-made motivations.
Begin the plot mid-journey (so theres no waiting around).
Don't give opportunities to stop or rest without immediate hazards.
Make sure theres always a reason to keep the moving forward (a Macguffin often helps here, or some timed event that they are hard pressed to ever meet).
Minimal, pre-timed combat encounters (depending on time).


Thats what I go for anyway.