A letter of recommendation for National Honor Society should include an introduction of the writer and their relationship with the student, a brief summary of the student's academic achievements, leadership qualities, character traits, and involvement in extracurricular activities. The writer should provide specific examples and anecdotes to support their claims and showcase the student's strengths. The letter should also explain why the writer believes the student is an ideal candidate for the National Honor Society and how their inclusion would benefit the organization. The letter should be written in a professional tone and formatted appropriately, with the writer's contact information and signature included at the end.