tating that the written portion of a judge test isn't difficult would be a lie. The truth is that they're actually really hard. Learning the rules well enough to pass one of those is not an easy task. The Comprehensive Rules is a large document by itself, and the other DCI documents add up more material to an already long compendium.
I've seen several individuals failing a written test because they underestimated it and didn't prepare well enough. I've noticed that quite often it's not that someone is just "bad at rules" or didn't study enough; it's that the studying methods they're using aren't adequate for them. We all have different ways of learning, and what's useful for some might be less efficient for others. Over the past few years, I've learned of many different study techniques that I'd like to share with everyone who's planning to undergo a judge test in the future, or who'd just like to get a better grasp on the rules.
Get a mentor.
This is not precisely needed, but I'll mention it from the start. Having a mentor with whom you can discuss the rules and throw questions at is going to be an immense advantage. The learning curve will be a lot faster. If you live in an already mature community, talk to the judge that you think is better at rules and mentoring, or the one that you find yourself most comfortable with. If there are no judges nearby, you can look up in the Judge Center to find judges relatively close to you; "close" doesn't mean "geographically close" only, as it could also mean culturally close, or close regarding the language you both speak. Do not hesitate to contact them: all judges understand that part of their judgely duties is to help other people become better judges!
Find a friend to study with.
As an alternative if you can't find a mentor, you can talk to that friend of yours who likes the rules and/or judging as much as you about studying together. Is there anything more stimulating than challenging a friend? Find difficult situations for your friend, and ask him/her to do the same for you. You could propose running a fun competition, and the winner of the week gets a beer/pizza/anything else. It will take you just a few weeks to become a real guru.
Surf on the boards.
There are boards dedicated to rules on almost all Magic websites, in almost all languages. Having to face many specific questions coming from specific card interactions and then having to go back to the basics of the rules to find an answer to numerous questions is a great way to identify better rules interactions and understand better how they work. Obviously, this works even better when you try to find the answer by yourself before reading the one made by whoever is the rules guru in charge of the board.
The Judge Center is an extremely valuable tool, and its practice tests are very good for studying purposes. You'll always find something that you didn't know in the questions, and you can learn a lot if you pay attention to the explanations and the parts of the rules cited. These tests also give you an idea of what the real deal is. Yes, the format of the actual tests are exactly the same – it's the questions that change. I highly recommend to anyone planning to test for L1 to pass the Rules Advisor test, as this will entitle access to MTGRULES-L, the Magic rules mailing list, which is another valuable resource. It will also send a clear message to whoever might be testing you that you're taking this seriously – many testers expect you to be already a Rules Advisor. Be careful, though: although it seems easier and more accessible, taking tests is generally not the best way to start learning rules.
Read the rules completely.
This one is obvious, but highly underrated. You should read each one of the documents at least once. You'll notice that there are so many things that you didn't know, and I suggest not ignoring parts of them that look "obvious." A common mistake I've noticed is that people ignore section 5 of the CR (Turn Structure) because they think they already know what's in there. Sure, as players, we all know that it's untap, upkeep, draw, main, etc., but do you really know what happens in the cleanup step, or what the proper names for each phase and step are? That's all described at length in that section.
Delete what you know.
Download the Word version of the Comprehensive Rules, and start reading it on your computer. Delete every paragraph that you already know. You'll end up with a copy with all of the things you haven't learned yet. Study from it, and keep deleting what you find that you've already learned. Another take is to copy everything you don't know yet into a separate, blank document.
Find actual examples.
The rules can be very abstract. You might read a paragraph, find that what's written in there makes sense, and move forward, without actually knowing what it all means and how and when to apply it to the game. Try to find actual game examples for the rules you read, and if you can't find one, then you know you have to think a bit more about it. Once you find an example, it should be easier for you to understand what the rule means. This goes well with the previous technique. You can establish that you need to find an example before you delete a paragraph.
Write notes on a working copy.
Print a copy of the rules, and write notes on the margins. You can write questions you might have, what you think are examples for specific parts, etc. You can then use them to further investigate, discuss it with other judges and/or your mentors, or reference them later.
Look for situations that might look similar, but are not.
It's fairly easy to mistake how some cards interact when the situation seems very similar to one that you already know. Looking for these, and understanding what makes them different will give you a better understanding of some rules that might be not so commonly used. For example, do you know what's the difference between the interaction of an Urborg, Tomb of Yawgmoth and a Blood Moon versus an animated Urborg, Tomb of Yawgmoth (perhaps with Animate Land) and Ovinize? What about the difference between Rival's Duel and Spikeshot Goblin when one of the creatures targeted by Rival's Duel leaves play in response to the spell versus Spikeshot Goblin leaving play in response its own ability?
Make lists and use acronyms.
There are several things in the rules that can be summed up in a bulleted or ordered list. For example, the steps to play a spell or ability, the state-based actions, the turn structure, the interaction of continuous effects (aka layers), among others. Studying from such a list should make it easier. Also, once you have a list, you can easily create an acronym that makes it easier for you to remember it, like the popular DEBT for protection (Damage, Enchanted, Blocked, Targeted). Ute Kronnenberg, from Germany published an article on using mnemonics not long ago, and I recommend reading it.
Play the game!
The more you play the game, the more exposed you are to interesting card interactions. Even more so if you build decks to ensure that such interactions will come up. A deck full of Snakeforms, Giant Growths, Glorious Anthems, Figures of Destiny, and Mirroweaves will surely provide hilarious situations, while at the same time train you in the dark secrets of the dreaded layers. Playing the game increases your familiarity with the cards as well, which makes you a better judge in general. You could also play in Magic Online, in which you get the added benefit of watching precisely how some things work, like the turn structure, priority, and the stack.
There is a myriad of online resources that you can mine for knowledge. Here are a couple of them:
* The DCI webpage has the Comprehensive Rules and DCI documents available for download.
* The #mtgjudge IRC channel, on the EfNet server.
* WotC's MTG-L mailing list, which is open.
* If you have access to WotC's closed mailing lists, such as MTGRULES-L or DCIJUDGE-L, you can always browse the LISTSERV archives to read older posts and to search for specific rules and/or card interactions.
* Periodic rules and/or judging columns, like Cranial Insertion or The Riki Rules (bonus, if you're a native Spanish-speaker, you might want to check the Spanish version of Cranial Insertion.)
* Have I mentioned already how wonderful the Judge Center is? =)
I'm sure there are many other ways to study than the ones I've presented, and perhaps there's one that works better for you. In that case, feel free to plunge into the boards to share it with the rest of the world!