How to Begin a Letter
When beginning a letter, leave a blank line under your header, align your salutation with the left edge of the paper, and leave a blank line between it and the body of the letter. Also, make sure to end your salutation with a comma. When writing your salutation, “Dear” is suitable for a formal or casual letter. If you include a title, use the recipient's last name, for example, “Dear Mr. Smith.” If you're unsure of the gender of your recipient, use “Sir or Madam.”
Write your return address (and, optionally, your name) in the top left corner. Formal letters have somewhat long, detailed headers which contain both your own personal information and the information of the person you are contacting. Provide as much of this information as you are able to. The first thing you should do is to write your address (and/or your name) in the top left corner. Write the address in standard two-line form - in other words, put your street address in the very top left corner and your city, state, and postal code on the line below it. If you choose to include your name, which is not required, put it in the very top left, rather than your address, which will then occupy the second and third lines. Here is a sample of how we might write our name and address: John Smith 21 Jump Street Milwaukee, WI, 12345 Write the date below your contact information. Next, write the current date. Skip a line below your address, then write the date so that it's similarly aligned with the left edge of the page. Dates are written in the form: month, day, year. Always spell out the month of the date, but not the day or year. Here is a sample date of this form: April 1st, 2014 Write the "inside address" below the date. Finally, you must specify the name and address of the person you're attempting to contact. This is called the "inside address" because it's the same information as on the outside of the envelope, only inside it instead. Skip a line below the date and write this aligned with the left edge of the page as well. If you know the name of the person you're contacting, lead with this. If not, try to at least include his or her title (like, for instance, "Professor of English Literature" or "Senior Technician"). If you know both, write the name first, then the title on the next line. If you're writing to this person at his or her place of employment, next, write the name of this place. Finally, write your recipient's address on the following lines. Here is an example of an inside address: Mrs. Jane Doe Director of Stadium Operations Wrigley Field 1060 West Addison Street Chicago, IL, 98765 Consider using an alternate header arrangement. The instructions above aren't the sole way to compose a header in a formal letter. Other options are acceptable as well. The most common alternative to the method above is to position your return address in the top right corner, rather than the top left corner, and to position the date under the inside address, rather than above it. In other words, in this alternative configuration, the return address is in the top right corner, followed by a skipped line, followed by the inside address aligned with the left side of the page, followed by another skipped line, followed by the date. For casual letters, simply write the date alone. The above instructions assume you're writing a letter in a formal or business context. If you're simply writing a letter to a friend or casual acquaintance, you may want to skip the pretense of a formal header. If so, simply writing the date in the top left corner is sufficient. After this, you may proceed to the salutation and the body of the letter itself. Skip a line after the header to position the salutation properly. The salutation is the greeting that begins a letter - "Dear distinguished colleague,", "My true love,", and so on. You have a variety of choices when it comes to salutations, each of which may be appropriate for certain occasions and not for others. Whichever salutation you choose, make sure you align it with the left edge of the paper and leave a blank line on either side of it (in other words, have blank lines between it, the header, and the body of the letter). Note that salutations almost always end with a comma. In the U.S., you should typically use a colon instead of a comma after the salutation when writing a business letter. When in doubt, use "Dear". If you ever have any doubts about which salutation to use, the standard "Dear [Name and/or title]," works wonders. This salutation is suitable for letters ranging from formal to casual and from grave to content. If you include a title, use only your recipient's last name. For instance, "Dear Mr. Smith," is correct, while "Dear Mr. John Smith," is somewhat unusual. For example, we might begin our letter to Jane Doe with the simple "Dear Mrs. Doe,". If we want, we can include her title: "Dear Director Doe,". Account for uncertainties about your recipient. Sometimes, it's impossible to know exactly who will be receiving your letter, such as when you're writing to a department of a large institution. In these cases, it's important to make sure that your salutation takes your uncertainties into account so as not to make an unfair assumption about the recipient. Below are some common situations in which you'll need to account for unknowns: If you're unsure of the gender of your recipient, use "Dear Sir or Madam", or simply use their full name (i.e., "Dear Lee Anderson,") If you don't know whether you're writing to a man or a woman, but you know your recipient's title, you may use it instead (like "Dear Professor,", "Dear Senator,", etc.). If you don't know a female recipient's marital status, use "Ms.", rather than "Mrs.", as in "Dear Ms. Norton,". Finally, if you are sending a letter to a business or institution rather than to a specific person within the business or institution, you may want to use "To whom it may concern," rather than a traditional salutation. Some find this salutation undesirable - it is also acceptable to use "Dear [Name of Institution]," though this is somewhat informal. Use informal salutations only in casual or intimate contexts. While you'll generally want to stick to "Dear" salutations in most formal and semi-formal contexts, if you're writing to a close friend, significant other, or family member, you can usually get away with informal salutations. Because you're no longer bound by rules of etiquette in these situations, you have a wide variety of options at your disposal. Below are just a few: If you're writing to a good friend or a close family member, you may want to use a nickname or pet name in your salutation ("Dear Gator,", "Dear Fonz,", etc.) If you're writing to a lover or significant other, you can be flowery and affectionate in your salutation, though you don't have to be. "My true love," "Dear Smooshums," and "To my one and only angel," are just as valid as simpler romantic salutations, like simply writing your recipient's name, followed by a comma (i.e. "John," or "Jane,") 
Write your return address (and, optionally, your name) in the top left corner. Write the date below your contact information. Write the "inside address" below the date. Consider using an alternate header arrangement. For casual letters, simply write the date alone. Skip a line after the header to position the salutation properly. When in doubt, use "Dear". Account for uncertainties about your recipient. Use informal salutations only in casual or intimate contexts. 