Identify and explain one troubleshooting tip or technique

Identify and explain one troubleshooting tip or technique.
One method for troubleshooting method is reviewing your work, many times we as humans will perform maintenance and we make errors, we are prone to it. Reviewing our work is a good method to make sure that the issue is not due to human error.
Identify in which step (analysis, planning, measuring) the technique would be applied.
This technique should be applied as soon as you perform the solder, because it would make no sense to review something that is not present.
Not every tip will apply to every situation. Explain a situation in which your tip would be applicable (include personal examples if possible).
My tip should be applicable in all situations except in the conditions that you have reviewed your own work and you are satisfied and said work has been supervised and reviewed by fellow peers. Having multiple opinions is always helpful to better yourself because you can use their advice as constructive criticism.
Identify one potential impact of poor soldering on a printed circuit board. How would you identify the fault?
A poor fault I can foresee due to poor soldering would be a resistor not functioning correctly or something that should be functioning in a certain manner is not.