One Rule to Rule Them All
If you are a player who is interested in UNDERSTANDING chess a bit more rather than HOPING your opponent will make a mistake, then this rule is for you.Imagine chess to be a real life game, without any turns. How quick would each piece be?
A Queen would be like a highly skilled athlete, twisting and turning. A Pawn would be like a sack of sand that needs to be dragged around.
Let's put the different chess pieces on an empty board.

A Queen can get anywhere within 1 or 2 moves. A Rook too. A Bishop too, but only on its own color. But a Knight needs to hop around for a while to get somewhere. A King is even slower. And a Pawn... it cannot even get to most places... and when it moves it can never return.
Now let's put a couple of Pawns on the board. All of a sudden a Rook is limited, while a Queen can still get anywhere in 2 moves.
If you put even more pawns, the Queen loses much of her speed too.

So where am I going with this?
Chess is a game with varying speed. The more pawns, the slower. The more athletic pieces, the quicker.
If you understand the impact of this, you have come a long way in understanding chess strategy.
Let's try to understand some basic rules:
"A Knight likes closed positions" (with many pawns it's not slower than other pieces!)
"A King needs to be in the corner" (you wouldn't place your grandfather in the middle of a battlefield right? He would only stand in the way! (besides being vulnerable))
"Bishops like an open board" (if you would place a sniper on a battlefield, you wouldn't put it in a maze would you?)
Q: Have you ever wondered why Grand Masters move pieces mysteriously backwards?
A: Because perhaps it's a SLOW position (many pawns).
Q: Have you ever wondered why the computer says your Pawn move is a mistake?
A: Because perhaps the Pawn wants to move backwards later (and poor Pawns cannot).
Q: Have you ever wondered why the computer wants you to give up your Rook for a Bishop without any clear reason?
A: Because perhaps the straight lines are blocked by Pawns while the diagonals are open.
One Rule to Rule them all:
Chess is a game of varying speed.
Some positions are quick, some are slow.
Some pieces are quick and you need to use their advantage.
Some pieces are slow and you need to limit their disadvantage.
Like in life, some days feel like an hour, and some hours feel like a day.