I agree with post #2. Jigsaw puzzles require people to see both the forest and the trees, and it's easy to let one obscure the other. I think the best suggestion is to begin breaking the puzzle into smaller chunks, and organizing it as the previous poster said, by color, is perhaps the best way. There is nothing wrong with looking back at the overall design of the puzzle to make things easier either. While strategies like these are important to putting together large, complex puzzles, I think patience and perseverence are equally crucial.