1. Use a capital letter for the personal pronoun 'I':

What can I say?
2. Use a capital letter to begin a sentence or to begin speech:

The man arrived. He sat down.
Suddenly Mary asked, "Do you love me?"
3. Use capital letters for many abbreviations and acronyms:

G.M.T. or GMT (Greenwich Mean Time)
N.A.T.O. or NATO or Nato (North Atlantic Treaty Organization)
4. Use a capital letter for days of the week, months of the year, holidays:

Monday, Tuesday
January, February
Christmas
Armistice Day
5. Use a capital letter for countries, languages & nationalities, religions:

China, France
Japanese, English
Christianity, Buddhism
6. Use a capital letter for people's names and titles:

Anthony, Ram, William Shakespeare
Professor Jones, Dr Smith
Captain Kirk, King Henry VIII
7. Use a capital letter for trade-marks and names of companies and other organizations:

Pepsi Cola, Walkman
Microsoft Corporation, Toyota
the United Nations, the Red Cross
8. Use a capital letter for places and monuments:

London, Paris, the Latin Quarter
the Eiffel Tower, St Paul's Cathedral
Buckingham Palace, the White House
Oxford Street, Fifth Avenue
Jupiter, Mars, Syrius
Asia, the Middle East, the North Pole
9. Use a capital letter for names of vehicles like ships, trains and spacecraft:

the Titanic
the Orient Express, the Flying Scotsman
Challenger 2, the Enterprise
10. Use a capital letter for titles of books, poems, songs, plays, films etc:

War And Peace
If, Futility
Like a Virgin
The Taming of the Shrew
The Lion King, Gone With The Wind
11. Use capitals letters (sometimes!) for headings, titles of articles, books etc, and newspaper headlines:

HOW TO WIN AT POKER
Chapter 2: CLINTON'S EARLY LIFE
LIFE FOUND ON MARS!
MAN BITES DOG