To answer the question: “What is the best chess strategy?” is not so easy.
There is no simple answer. Every chess position requires a different plan or approach.
However, I can give you many general guidelines you should follow while playing a game of chess.
1. Don’t get out with your queen early in the opening! If you do that your queen will be chased around by your opponents pieces and you lose developmwnt time. Your opponent will develop fast by attacking your queen with his developing pieces. In other words your development is ZERO because you have to retreat with your queen all the time and at the same time he develops piece after piece. Soon you are going to run behind in development. He will have many of his pieces out, controlling the center, but you will just have your queen out. This is ridiculous. Your queen can’t do anything anyway on its own.
2. Learn a decent opening and play it all the time to get better at it. Don’t switch openings in every game. Don’t just make a move, but study the whole opening system until you know what you are doing. Specialize in some openings, select some for White and for Black. Try to reduce your workload.
For example: When you have White you play 1.e4 all the time and when Black answers with 1…e5 followed by Nc6 then you play the Ruy Lopez (Spanish opening) all the time.
When Black plays the French (1.e4 e6) you select a variation of the French which you have studied before.
When Black plays the Sicilian Defence (1.e4 c5) you prepare something for it. Maybe play the Kings Indian Attack (1.e4 c5 followed by the setup Nf3, g3, Bg2 etc., then you don’t have to learn all the Sicilian Defence Variations like the Dragon, the Paulsen System, the Scheveningen etc.. this saves time.
When Black answers your 1.e4 with the Caro Kann 1…c6 you prepare a line against it at home that you study in depth and play it all the time until you are an expert at it.
3. Buy books about chess strategy especially about deep positional chess.
4. When you have lost, study your mistakes always and don’t repeat them in your next game. This is very important. Next time play the same variation again, but play it better. Do not switch to another opening just because you have lost, but study this line again until you know what went wrong, and play this line again and again in your next games.
5. Don’t learn dubious openings, but study and play what grandmasters play. Grandmasters don’t play dubious amateur openings because they want to win.