1. Get your pieces out into the center quickly. The opening is a race to see who can get their pieces out first while keeping at least a share of control of the center. This is the main point to remember; all the other rules are just footnotes to this one
2. More detail on winning the race:
a. Move pieces, not pawns, and
b. Move them to their best squares in one move if you can, and also
c. Try to gain time if you can with aggressive moves.
3. Move minor pieces out first, not your Queen or Rooks which can be attacked and lose time
4. Get a firm foothold in the center and don't give it up
5. Generally move Knights straightaway to f3/c3 or f6/c6
6. Move your king to safety at the side by castling King's-side (which also gets your Rook into play)
7. Complete your development before moving a piece twice or starting an attack
8. Keep your queen safe
9. Don't grab pawns or attack if you haven't completed development
10. What to do if you are ahead/behind in development:
a. If you are ahead in development, start something going and open up lines for your better
pieces
b. If you are behind in development, don't start anything and keep things closed until you
have caught up