You will encounter bonus puzzles right before your next checkpoint level. The earlier ones are generally easier to figure out than your later ones. My best tip for this is to start a game and get to the puzzle level. Try to finish it, once done, quit back to the menu and get there again. If it’s the same puzzle, just quit and try again because it won’t count if you finish the exact same puzzle twice. Once you start to see that you are getting repeats a lot, get to the first checkpoint and go for the next puzzle level. Attempt that one, then quit and restart from the checkpoint. Repeat this process as much as necessary until you’ve solved 10 puzzles.