A common IF set-piece is imprisonment of the PC, usually in a single room with few apparent features; to advance the plot, a means of escape must be found. Multiple solutions are rare but not unknown in this kind of puzzle.
- If there is a guard of some kind within sight, you may be able to trick or deal with them somehow. If there isn't a guard, try attracting the attention of one by making noise.
- Examine every mentioned object - the bars over the window, the floor, yourself - in minute detail.
- If all else fails, sometimes an NPC will eventually come and let you out. But don't count on it.