Instructions
Lay out the pieces face up where you can see them easily. You're going to search through the pieces many times, and it will much easier when you can see them all.
Find sections of pieces that are easy to identify. For example, if a bird is the only red thing in the puzzle, you can easily find the bird pieces by looking for red. Most puzzles have straight edges, which makes the edge pieces easy to identify by shape.
Put the sections together as you find them. You will probably have several completed sections of the puzzle that grow as you find more pieces.
Look for pieces to connect the sections to each other. Once you start connecting sections, you'll go from having a few completed sections to having a few holes in an otherwise completed puzzle.
Fill in the last "holes" in the puzzle. These will probably be the hardest parts of the puzzle, but they will be easier to fill in now because you have fewer pieces to search through.