Hazards
Source GM Core pg. 35
Looking for and disarming hazards is a common exploration scene. Hazards shouldn't appear out of nowhere. A trap might be on a door's lock, a security checkpoint, or so on. Foreshadow traps with environmental clues, suspicious architecture, signs of the trap's past activations, and other signs. Remember that a surprise that's entirely unexpected is often very unsatisfying.
Simple hazards occur in exploration mode, but when a complex hazard triggers, move to exploration mode. When any hazard triggers, clearly depict what action by a PC set off the hazard, what happens as the hazard activates, and illustrate any aftereffects. Remember that a damaging hazard won't always have a huge effect. They tend to work best if their activation might alert creatures in the area, lock the PCs out of an area, or cause a similar narrative setback beyond just damage or another easily removed condition.
Simple hazards occur in exploration mode, but when a complex hazard triggers, move to exploration mode. When any hazard triggers, clearly depict what action by a PC set off the hazard, what happens as the hazard activates, and illustrate any aftereffects. Remember that a damaging hazard won't always have a huge effect. They tend to work best if their activation might alert creatures in the area, lock the PCs out of an area, or cause a similar narrative setback beyond just damage or another easily removed condition.
Searching for Traps
Source GM Core pg. 35
PCs have a better chance to detect hazards while exploring if they're using the Search activity (and the Detect Magic activity, in the case of some magic traps). If a PC detects a hazard and wants to disable it, slow down. Ask the player to describe what the PC is doing, and provide concrete details about how their efforts pan out to ramp up tension. If a hazard requires multiple checks to disable, describe what happens with each success to show incremental progress.