You should look into several things before making your employment letter. You should pay attention about the contents of your letter. You may want to deliver as much information about yourself without sounding that you are bragging.
You can do this by being courteous in the way you talk to the reader as this maybe your future employer. In addition, it is also good if you can include a recent work experiences. This is in addition to the ones that you are going to post in your resume.
Another tip when writing an employment letter is that to always include your aim in applying for the company or establishment. This will be a deciding factor for the employer to hire you or not. Therefore, you must make it look nice and appealing.