A cover letter is made up of several parts. Start by explaining why you responded to the ad, and talk briefly about what interests you most about the offer. This part should be short and serve as an introduction to the next one which is the most important and will make the difference. The entire letter should not be more than one page, go to the essentials. In most cases, it is better to remain neutral and not attempt too much originality. Avoid lying to adapt to what the recruiter is looking for, it will be seen very quickly if you get an interview and could ruin everything. Use appropriate vocabulary, specific words and company allusions that show you took a keen interest and took the time to research.
This second part consists of explaining why you are THE qualified person for this job. Start by quickly tracing your background and qualifications. Don't just repeat what you've already put on your resume, add a relevant phrase for each position you've held. This must show that you have acquired a skill or a useful quality for the job for which you are applying. Show that you can be useful to the company, what you can bring to it and not the opposite. Include the qualities sought in the ad and explain why you match the profile.
At the end of the letter, add a polite formula and a sentence highlighting your availability to meet the recruiter. If your cover letter is convincing and your CV original, the link to an interview should be natural.
