Before you begin the writing of your letter, you must first make sure to include the date. Dates in Spanish are written with the day first, then the month, then the year. Do not include the month first, especially if writing the month numerically, as you could create confusion. For example, 2-10-2010 in Spanish is actually the second day of October, 2010 and not February 10th, 2010.
Next, in either the left or right hand corner you must include the name and address of the recipient. You should include your name and address with the title "Remite" or "remitente" as the sender.
Regardless of the audience, you must include a greeting in your letter. If your letter is a formal one you can begin by using the following phrase: Estimado(a) ______. This literally translates as 'Esteemed _______.' You could also use Respetado ______, however this is much less common. Make to use the person's title when writing a formal letter. It should be Senor, Senora ____, or even a professional title like Licenciado (someone with a degree), or Inginiero (Engineer), depending on what their title is.
If you were writing a letter to a friend, you would not use such formalities as these but a simple Querido(a) _______ to open your letter.
As the teacher you can practice by giving out names, relationships, or situations in which a letter would be written. Students must choose whether or not to use Estimado ____ or Querido ______.