Reflect a can-do attitude
Right from the start of your cover letter, every word you use should reflect that you mean whatever you are saying. You should not make it sound like you are less than 100%. Try to sound as confident as you can, and let the reader think that you have what it takes to fill in the vacant position.
Start with experience
Your cover letter should start with the thing that concerns the reader the most. In your case, job experience. Since every employer who is looking to hire new employees wants to know how experienced the candidate is. Do not open the first paragraph by saying things like, how much you want this job because you think you are the right candidate for it. It does not impress the prospective employer.
Come across as being positive. If you are applying for a job that is considered tough in your respective industry, do not write: “I feel/think that I am confident enough to carry out that task/job”—it will give the impression that you are not fully confident, and you doubt your skills. Come right out of your shell and say: “I am fully capable of doing this job, as I know what it takes to get it done.”