Your cover letter is one of the most important parts of your application. If you are applying direct to an employer it will be one of the first, if not the first, things the hiring manager reads about you. It is therefore important to ensure that your cover letter portrays you in the best light and that it is accurate.
A common mistake is using the same cover letter and simply editing sections to try and make it applicable for different jobs. Recruiters can usually tell when this is happening as the letter is usually not tailored to the role or doesn't hold any relevant information. I've even received cover letters that relate to working at a different company!
It is important that the cover letter shows you are the best candidate for the job and therefore you should write one for each role that you apply to.
2. Cutting corners It’s not hard to tell when someone has edited a few words of a cover letter that they use for bulk applications. This tactic implies to the employer that you haven’t fully read the job description and do not have a real interest in the role. Put yourself in the employer’s shoes – if you put this little effort into your job application, how much effort are you realistically going to put in when you are in the role? Instead, use your cover letter to highlight your genuine interest and understanding of the role and provide a clear insight into how you would make a positive contribution and add value.