Take every piece off the board and leave the pawns where they stand. What is left tells you where the game is going, and it is what strong players look at first.
Here is one of the most common shapes in chess, the Carlsbad structure, which comes from the Exchange Queen’s Gambit and half a dozen other openings.
7 
2 
g The pawns choose the plan
White’s queenside pawns outnumber Black’s three to two, and the classical idea is not to make a passed pawn with them but to march them anyway: b2-b4-b5, hitting c6, so that after the trade Black is left with a weak pawn on the c-file or an isolated one on d5. Two pawns attacking three, which is why it is called the minority attack. Black meanwhile plays in the centre and at the king, with …Ne4 and …f5, because that is the side where his pawns can advance.
Neither plan is invented. Both are read off the skeleton. Same shape, same plan, whichever opening produced it.
The four faults worth knowing
Nearly every structural weakness is one of four: an isolated pawn with no neighbour to defend it, doubled pawns stacked on one file, a backward pawn stuck on a half-open file, and a hole, meaning a square no pawn of yours can ever cover again. On the other side of the ledger there is one asset that beats all four: a passed pawn.
Learn to spot those five things in ten seconds and you have most of positional chess. You will not always know what to do about them, but you will be looking at the right part of the board.
Pawns do not come back
This is the reason any of it matters. A knight on a silly square can return next move; a pawn cannot move backwards at all, so h3 or a6 is a decision you live with for the rest of the game.
So before a pawn move, ask what square it stops defending and whether you are happy never to have that square back. That question, asked honestly for a month, is worth more rating points than any opening you could memorise, and it is the sort of habit that gets people through a rating plateau.