This article was written by Code Junkie for the March 2013 WGA Newsletter:

Puzzle Caches – 101
I know there are many cachers out there that just ignore all those blue question mark caches (and may have already stopped reading this article already), but hopefully this article will provide you a few tips / tricks to help you along the way. This is a “101” article and will address the very basics of puzzle caches, but advanced topics will be covered in future articles.

Puzzle Types
Puzzles come in a variety of types (numbers, trivia, ciphers, etc.), so one important piece of solving a puzzle is to determine what type it is. Knowing this will help determine what “tools” are most likely to help solve it.
Numbers – The most common form of this is the Sudoku style. There are numerous tutorials (and solvers) available online to help with these. My best advice on these is to print them out on paper and work from the paper copy with a plain old pencil and eraser.
Trivia – This type of puzzle involves doing some kind of research to calculate coordinates. Most “Field Solve” puzzles fit into this category because you’re asked to collect information (i.e. trivia) at some predefined spot. Online search engines (Google is my favorite) can be your best friend for these types of puzzles.
Ciphers – This type of puzzle requires you to use sort of formula or algorithm to convert gibberish text into readable text. These can be extremely difficult to do by hand, so the best option is to use the online cipher tools to help you with these.

Tips / Tricks
The 2 Mile Rule – Generally puzzle finals are within a 2 mile radius of the published “bogus” location. This can help narrow down possible locations for the cache.
Keep Good Notes – Keep notes of methods you’ve tried, coordinates you’ve entered in the geocheckers, etc. The cache page allows you to enter notes as does GSAK (Geocaching Swiss Army Knife). If you’re using a paper printout be sure to always write the cache ID on the paper so you know which cache it is.
Ask the CO – Feel free to contact the Cache Owner (CO) for help. This is where the “notes” you keep come in handy. You can share these with the CO to explain what you’ve tried so far and many times you’ll discover you have the right method, but missed something minor that can easily be corrected.
“Google” – Google (or your preferred search engine) should be your friend. This is going to be your friend for solving those “trivia” type puzzles, but can also be used for much more.