From recent First informal emails - be careful when using "local" names. Make sure your reader knows what you're talking about. Examples: "Don't forget to visit El rastro." - Could be better. "Don't forget to visit 'El rastro' which is a huge market." Better! "You can always visit the Prado or the Reina Sofia" - Could be clearer. "I know you like galleries, so you can always visit two of our most famous ones, the Prado and the Reine Sofia" - Much clearer (although longer of course).