Capitalization 

Utah State Core Standard 2, Objective 3b.  Correct capitalization of sentence beginnings and proper nouns.

Jeff Anderson (in Everyday Editing) suggests that students need to know about these reasons to capitalize: 

•    Proper nouns
     - - specific names of people
          - - specific places such as cities, states, countries, stores, restaurants
               - - Brand names
•   Proper adjectives
      -- Proper nouns used as adjectives   (Adjectives are words that describe or modify nouns.)
•   Titles  
     -- books
     -- songs
     -- TV shows and movies
     -- poems
•   first word of a direct quotation
     -- dialogue
     -- quotes from other works when it's the entire sentence
•   titles used before a person's name
     -- professional titles
     -- government titles
     -- personal titles

initialisms (DVD)

And, of course, the beginning of a sentence. 

Anderson also shares misunderstandings you may need to clarify:
•    Confusion about what makes things specific enough for capitalization (wanting to capitalize oak because it's a specific type of tree)
•   Students who write in all capital letters (all caps) -- Don't do it.
•   The height ratio between a capital letter and a lowercase letter -- The capital letter is about twice as high as the lower case letter. 

Recognize a proper noun when you see one.  Nouns name people, places, and things. Every noun can further be classified as common or proper. A proper noun has two distinctive features: 1) it will name a specific [usually a one-of-a-kind] item, and 2) it will begin with a capital letter no matter where it occurs in a sentence. 

This shows differences between capitalization in English and capitalization in español:  http://www.elearnspanishlanguage.com/grammar/capitalization.html

This names some of the times you capitalize.