When you fail a skill check, you can attempt to re-do the check. Doing so allows you to redo the check at disadvantage.

 

Be aware however, if you fail a second time, you may experience mishaps. A second attempt picking a lock may cost time or fully jam the locking mechanism. Failing a seond time to disarm a trap may trigger it.

In some cases, the dice are unforgiving. In this case, you could "Take 10".

In this case, as long as the task is within your character's ability, you can succeed at the task, but it takes 10 times the regular length of time.

As an example, a trap that takes 1 minute to disarm properly would take you 10 minutes instead. However, do remember that no amount of "Taking Ten" will turn an impossible task into a success.

Example:

Phoenix Hofstedder has a climb speed of 30 and is trying to scale a 300 foot cliff. With successful skill checks, this would take him 1 minute to successfully climb, But Phoenix worries about his athletic ability to scale such a steep cliff, taking a total of 10 minutes to climb the cliffface.