Source: http://www.college-go.org/blog/kim-myungwans-principles-of-go

Opening

• Take the corners
• Enclose or approach the corners
• Extend to the sides

Middle game

• Attacking your opponent’s weaknesses
• Defending your own weaknesses

Fighting

• Who’s got more stones?
• Who’s got more liberties? (Capturing race scenario)

Attacking

know why you are attacking; set the aggressiveness of your moves appropriately.

• You can get benefit elsewhere while attacking
• You can kill outright

Invading:

there are a few ways to save your stones. In order of preference, order of exploring possibilities:

• Counterattack. Disconnect and capture your opponent’s stones. Look for crosscut opportunities. Be aware of capturing races.
• Make a base, make territory while living
• Run into the center, connect to your other stones.
• Live inside, either by making two eyes or maybe seki.

Common kyu-player mistakes

• Contact plays are almost always a mistake.
• Think 3 seconds at minimum before playing a move. You will catch 80% of your mistakes this way. (Online games are bad because it’s too easy not to spend 3 seconds!)
• Focusing too much on one area. Don’t follow your opponent blindly, always look for ways to take sente.

Becoming dan level

• Reading. Always read 3 moves: your move, your opponent’s likely response, and how you will respond next.
• Always look for weaknesses in your opponent’s stones
• Try to make your stones globally efficient. Try to make your opponent’s stones inefficient.

Difference between territory and influence

• Territory is cash, worth the same in the beginning the game as at the end of the game.
• Influence is an investment for the future. It might not be useful near the end of the game, but it’s more valuable earlier in the game.

Making a Move

• Evaluate your position. Are you winning or losing? Play more aggressively if losing, play safely if winning. Where are you strong or weak? Where is your opponent strong or weak?
• Generate candidate moves
• Read through the likely outcome
• Evaluate the outcomes
• Compare the outcomes
• Choose the move that will let you win

Check the game that highlighted the principles, commented by Kim Myungwan himself: