**Avoid lack of choice and instant death**

You always need to have some tension of course. Peril generates excitement. But the players must always be in control and feel they have a chance.

Describing a rickety bridge may be peril enough, but has little chance of collapsing just by walking across. But if they face a battle at the end and a player has a choice of being careful (half speed) or running and requiring an Acrobatics check to avoid a gap in the floor...And even a failed check would just require a Dexterity save to grab the rope railing (and you may want a contingency plan, in case the player is *really* unlucky, such as a flying monster waiting to grab them for dinner, which actually allows the chance for the player to fight back at its nest!).

Carrying dangerous components can add a gradual peril. Perhaps if these components are uncovered or damaged or get too close to each other there is an effect that is obviously progressively dangerous. Maybe they start glowing and a generate a field that causes anyone in 30' to take 1d6 damage per round and suffer progressive levels of exhaustion (Con saves to avoid). Players (and any enemies) will recognise the danger but also know how to prevent it (probably).