Your letter writer should know you well enough to provide specific examples of times you displayed excellence at a task. There is a big difference between doing what people expect of you and going beyond the call of duty. Getting a sparkling recommendation that includes information such as this can put you ahead of other applicants. For example, if a teacher writes your recommendation, he should include information about your extra credit efforts for the class or specific examples of your work ethic.
A big section of the letter should belong to your skill set learned under the letter writer. This information must be relevant to the field of study in your graduate school. For example, if you are attending school for a degree in human resources, your letter of recommendation should include information relevant to that field; such as working with new recruits, selecting qualified people for a task and making policy recommendations. Have the letter writer explain that you completed these tasks with poise and precision. She should also include the length of her association with you.
Your letter writer should include some information in your letter to make you look more appealing. He should write some of the pleasant traits he noticed while you worked under him, such as enthusiasm to learn, thoroughness and strong leadership skills. Ask him to include specific instances when you exhibited the skills he mentioned, for added impact.
When your letter writer specifically states that she feels you are an ideal candidate for your desired position, it means she is giving the graduate school her professional promise. She is saying that she has experience in a specific field and she knows you are an ideal candidate for your study program. She should state it firmly that the field of study is the right course for you and you have all the necessary education to start learning immediately.