Do you especially want to gain insight into the applicant's professional and educational background? Then consider a standard application form. This not only lowers the threshold to apply, it also provides the necessary information in a structured way.
When processing the forms, you can initially choose to keep the candidate's personal data (e.g. name) invisible. This form of blind recruitment makes it easier to make objective decisions.
At least two independent evaluators carry out the selection of letters and CV’s.
While reading the letters, have a scorecard and note sheet at hand. So, you can record and process the collected information in a structured way. Which of the required competences or qualifications have been presented? Which job criteria have been met?
Certain names, previous education, previous work experiences or even places of birth can evoke positive or negative associations. So, while reading, be aware of your prejudices and bias.