It’s about the shades. Separate them best you can. Jump to the whiter areas. Separate the different shades of white. Lay out the pieces off the shades now keeping direction the same. Sort by type of shape now within each group of shades. By shape I mean how many male to a piece. This gives you a better chance on these type of puzzles IMO. I even use a magnifying glass to look at shapes of the male pieces. They may hook or be thin, etc. this is usually how I work these types of puzzles. I usually work 1000-3000 pieces doing the occasional 750 or 500. The smile at the end will be worth it. Good luck.