Covering letters are, in general, computer-printed. Your written application should always contain a formal covering letter in which you indicate the job offer that you are applying for. Make sure to include the correct address and name of the contact person.
Your CV must be short, to the point, chronological and complete. Your personal profile must be adapted to the job offer. No notes should be written on the documents that you send to the employer.
If you apply spontaneously, take the initiative to make sure that if there are no current vacancies your application will be stored in a database of potential candidates. If the company needs someone, this database is often the first to be consulted by the HR department.