A letter should have the recipient's address and the date on the right-hand side.
In a formal letter, if you don't know the person's name you should start "Dear Sir or Madam" and finish "Yours faithfully". If you know the surname it's "Dear Mr Brown" or "Dear Ms Brown" (some people still make a distinction between Miss and Mrs, but it's going out of date.) The traditional ending here is "Yours sincerely" and this is still much in use, especially by speakers of English as a second or business language. However, among native speakers it's often replaced by "Kind regards." When you know Mr or Ms Brown better, you might put "Best regards" instead. All this (except for the address) can also apply to email, although most emails are informal.
For informal letters there are fewer rules, though it's still usual to start with "Dear" ("Dear Jim") and to use a closing phrase such as "Best regards," "Yours" or (in some cases "Love.")
In a formal letter, if you don't know the person's name you should start "Dear Sir or Madam" and finish "Yours faithfully". If you know the surname it's "Dear Mr Brown" or "Dear Ms Brown" (some people still make a distinction between Miss and Mrs, but it's going out of date.) The traditional ending here is "Yours sincerely" and this is still much in use, especially by speakers of English as a second or business language. However, among native speakers it's often replaced by "Kind regards." When you know Mr or Ms Brown better, you might put "Best regards" instead. All this (except for the address) can also apply to email, although most emails are informal.
For informal letters there are fewer rules, though it's still usual to start with "Dear" ("Dear Jim") and to use a closing phrase such as "Best regards," "Yours" or (in some cases "Love.")