The first rule of puzzles without instructions is to trust the puzzle constructor. Constructors' goal isn't to stump you but to entertain you. If a puzzle is too hard, that's usually a sign of a poor constructor, not a poor solver.
Putting trust in the fact that the clues are all there, start looking through what you've been given to see what's going on. You should be able to figure out answers to at least some of the following questions:
1. Does the puzzle have a title? Is there some text that introduces the puzzle? Although it is rare to find outright instructions ("Put these words in alphabetical order), sometimes you'll get some sort of pun that points you in the right direction. A puzzle called "All Shook Up" might indicate that you will be solving anagrams or doing some sort of sorting.
2. What sort of raw information have you been given? Words, letters, numbers, shapes, or images? Arranged in lists, grids, or jumbled? Do you see any repeating information (like numbers in a sudoku grid) or sequential information (like the numbers in a connect-the-dots puzzle)?
In Puzzle C, for example, notice that each set of blanks has a single square shaded in. You need to figure out what is special about those letters. Will they, for example, spell a word?
3. Do you see any indication of the conclusion of the puzzle? Are there any signs – blanks, empty squares, or question marks are the most common – of where you will generate the answer and/or where to put the answer once you find it? Knowing where you're heading should give you some idea of what you have to do to get there.
For example, notice how, in addition to the 3 puzzles, you're also given – set clearly apart from the rest of the puzzles – one final puzzle element:
C B A =
This seems to indicate that everything will come together to steer you towards a specific goal. The repetition of the 3 puzzles' identifying letters would indicate that you'll need something from each puzzle to solve this final riddle.
4. Finally, think like a puzzle constructor. Most things that don't look as if they were deliberate usually end up being so. Small design decisions suddenly become very important when you're trying to steer your solvers in a very specific direction.—particularly if you're trying to do things fairly, and even more so when you are trying to make a puzzle that anyone could solve.
For example, if the constructor presents you with clues in alphabetical order, that would suggest that the answers will require a different order, or that the final order doesn't matter. If, however, you're given the clues out of alphabetical order, something else has determined the order of the clues. This is most clear in a crossword puzzle, when the clues are given in the order that they'll appear in the final grid. However, in puzzles without instructions like this one, constructors will sometimes arrange the clues so that the answers come in alphabetical order: a way to lend you an extra hand in solving.
For example, notice that the 3 puzzles here are given in a very specific order – A, B, C – but the letters at the end give that same sequence in reverse. It would have been much easier to either reverse the order of the puzzles (C, B, A) or give the letters at the bottom in alphabetical order. This means that the constructor was dealing with two different constraints: one that required the 3 puzzles to be presented in this specific order, but also one that required a different order when they all work together to bring you to the final solution.
Often, these constraints won't become clear until you're well into solving the puzzle. However, whenever it becomes clear what constraints the puzzle constructor was working under, it's a good way to verify that you're on the right track.
Once you've gotten the lay of the land, the next step is to start looking for patterns. You're almost always presented with a collection of objects that seem random. Start looking for different ways they might fit together. Given a list of words, you might check if you they can be alphabetized (apple, ball, candy, dog) or if they can be grouped into different categories (apple, cherry, and pear versus asparagus, broccoli, and spinach). If you get two very different elements – for example, a group of words and a group of images – count them: if there are the same number of each, you'll probably be pairing them up.
For example, Puzzle A gives you a list of five words and five crossword-puzzle-style clues underneath. Does each clue connect to one of the words?
As you start making these connections, see if you reveal any new information. For example, the six words
car chart mine range redo reuse
. . . seem random until you begin pairing them off:
car-mine chart-reuse redo-range
You now know that the theme of the puzzle is colors.
Now you can: