It depends what you are struggling with specifically, but I'd say the biggest help to crossing the 1000 barrier is:
- studying basic checkmate patterns and theoretical endgames (my YouTube channel has videos on several endgames)
- Following "opening principles" https://www.chess.com/blog/KeSetoKaiba/opening-principles-again
- When solving puzzles, try to understand the main themes and elements of the position, rather than just guessing through the moves. See if you can visualize/calculate the entire solution before playing the first move if possible.
What is the best way to advanced past 1000? I want to optimize my time studying and cannot advance no matter how many puzzles or games I play. Any advice is much appreciated!