In the beginning, there can be only one goal
From the start position, there can be only one goal. Attack the King! For the simple reason, that there is no other weak target in the enemy camp that is slow enough and vulnerable enough to go for.
In order to attack the King, you must create the LoA's towards the focal points near the King, and towards the defenders of those LoA's (lines of attack).
Where are the focal points
There are three places where the King can be, in the middle, castled kingside and castled queenside. This means, that your attackers must be flexible. Chess is a game of multi purpose moves. If you fulfil two goals with one move, and the enemy can only defend against one with his next move, you are making progress.
Creating a landscape of pivotal points
In the opening and the middlegame, you work on creating the LoA's. You have to have a plan for every piece. How is your rook on a1 going to participate in the attack? Do you need a rooklift via a3-g3 towards the focal point g7? Or should it go via the pivotal points d1-d3-g3-g7?
The pawn landscape
The pawns determine which lines of attack are open, which remain closed and where the outposts are. They determine the pivotal points where your attackers can turn their face towards the focal points near the enemy King or to the defenders of those focal points.
Contribution to the LoA landscape
There are a lot of positional concepts that are rather vague.
- Piece activity
- Central occupation
- Rook on open file
- Good and bad bishops
- Break through
- Space advantage
- the King feels obliged to leave the middle of the board in order to escape the pressure. That is already a success in itself, since a castled King cannot escape the coming onslaught anymore by castling.
- defenders become tight down by the things they must defend. That is where tactics might start to manifest.
- pawn moves are provoked because lines of attack must be closed. But pawn moves leave weak squares in their wake. Which might open up new points of pressure.
- Mate might threaten. Which can cause the opponent to lose wood in order to prevent it.
- You might be able to convert to a favourable endgame at will. Notice that you must only be able to get a favourable endgame, but you must be able to do so with enough time on the clock to play that very endgame.