Study games by masters of these openings. For the London, look at Vladislav Artemiev; for the Catalan, study Vladimir Kramnik.

Whether you find the exact legendary PDF or build your own from the 18 verified lines above, the result is the same. You will sit at the board with White, play 1.e4 or 1.d4 with confidence, and watch your opponent squirm.

Given the complexity and the evolving nature of chess theory, your repertoire should evolve. Regularly revisiting and refining your understanding of your openings, along with analyzing master games and current trends, will keep your repertoire both cunning and effective.