When applying for any position, it is essential to match both your skills and your personal and professional experience to the role in order to show you are a quality candidate.
No cutting and pasting
It's important to respond to each job vacancy individually - stock answers and cut and pasting won't gain you any advantage. So, for example, if a person specification asks for someone with 'strong customer service skills', highlight a very specific occasion on which you demonstrated such skills.
Spell it out
Additionally, make it clear which requirement of the person specification you are responding to. You might write: 'During my time as a call handler for Barclay's Bank, I often demonstrated my strong customer service skills in dealing with demanding members of the public.' Work your way through both the person specification and the job role answering all of the criteria in this way and you stand a good chance to securing an interview and, ultimately, a job.