A while ago Nick Hable wrote an article for the judges' page titled "Taking the Plunge." His article was about what you need to do once you have decided to become a judge. In that piece he listed six things that a person should do and / or learn. They are: 1) Learn the Comprehensive Rules, 2) Learn the Universal Floor Rules, Magic Floor Rules and Penalty Guidelines, 3) Get to know the level 3 judge in your area and tournament organizer's you may work with, 4) Don't lose touch with the players, 5) Improve your communication skills and 6) Be confident in your abilities.
I think his article provides an excellent synopsis on what you need to do and learn in order to become a good judge. As with most things the best way to learn new skills and improve the ones you have is with practice. However judging tournaments to obtain this practice may be difficult. Perhaps you may not have enough tournaments in your area or you can not afford to dedicate large blocks of time to working tournaments on a regular basis. Well lucky for you there is another way to gain experience in these areas; the Internet can help you out. (Is there anything the Internet can't do?) Just as players can use MTG Online to practice and play test for an upcoming PTQ, you can answer questions online to help you stay sharp so you can judge that same PTQ.
There are several message boards and newsgroups across the web that have forums dedicated to Magic rules. Some of these boards receive hundreds of posts on a daily basis. With the exception of suggestion # 3 above, getting to know your local level 3 and other tournament organizers, answering questions online can help you take the steps necessary to becoming a judge, give you practice before you take the test for the next certification level, or just make you a better judge.
Learning the Comprehensive Rules (and the Oracle)
There is nothing like looking through the Comprehensive Rules on a regular basis to help you get familiar with it. As a judge you shouldn't have to look up the rules every time that you give a ruling. In theory you should be able to answer most questions, both online and in tournaments, by using your knowledge and memory. However in replying online you can help get your point across if you quote the relevant section of the comprehensive rules at the end of your reply. You can respond to a question with a simple yes or no, and sometimes that is really all that is needed. However I find that it is much more helpful to include the extra information in your reply that just might answer a follow-up question before it is asked.
I will often post the official current Oracle text in my responses as well. Often a player will have only the original version of a card and he won't be able to understand why it does not work the way he thinks it should. Just like the Comprehensive Rules, using the Oracle on a regular basis will help you remember the official text of cards better.
Also it's one thing to know the rules; it's another thing to know that section 410 is about Handling Triggered Abilities. I'm not saying that you need to, or even should, memorize the rules chapter and verse. But having a better familiarity with how the Comprehensive Rulebook is organized can help you use it more efficiently.
Learning the Tournament Rules (Universal Floor Rules, Magic Floor Rules and Penalty Guidelines)
Questions that concern these documents do not come up as often as those about the rules of the game itself. However questions regarding time lengths, REL levels, shuffling techniques, marked cards and penalties do appear on a regular basis. When they do it is often judges that need to answer these questions. There are plenty of non-judge rules gurus that do not know the tournament rules as well as they know the rules of the game. Just as I often quote Comprehensive Rules at the end of a post, I sometimes include sections of the Floor Rules and Penalty Guidelines.
Don't lose touch with the players
It is almost impossible to lose touch with the general Magic playing population when you answer questions online on a regular basis. The variety of players that post questions online is amazing. One minute you will answer a question from a new player from South Africa who has only played multi-player casual games with his brothers, and the next you will answer one from someone in California who has played for seven years and wants to know if a 'combo' he is thinking of playing at the next PTQ actually works. As a whole I find that the more common questions I answer online are also common questions at tournaments.
The general population asking questions online may be a bit more casual than those that actually show up for at tournaments, but keep in mind that many of these casual players will start going to tournaments soon. I can only assume that the record numbers who have shown up at recent State Championships and Regionals tournaments and the increased popularity of Friday Night Magic is partially due to former casual players becoming more competitive. And by helping a player understand the rules, he may become more likely to go to tournaments. Answering a casual player's questions online today will spare a judge tomorrow.
Improve your communication skills
There is no better way to learn how to explain how the game works then by actually doing it, over and over again. After answering the same question repeatedly you start finding ways of doing it more succinctly.
The players online who ask questions are a diverse crowd and the techniques needed to explain the rules are just as diverse. I have seen plenty of examples where one question is asked and three people will post a response within seconds of each other, all with the same correct answer. However the person who asked the question will then reply with thanks and that it was actually the second person to answer that got the point across. You may have to leave out some of the technical jargon when settling a dispute especially if a player is newer and may not exactly comprehend what priority is. Or conversely, sometimes someone really needs to hear specific 'legalistic' words in order to understand the situation. With practice you can learn a lot of different ways of stating the same principle. You can also learn how to assess a player's knowledge and how to effectively communicate with him.
One way that I and a lot of other people explain complex situations is to use analogies. One scenario that I see repeated often is comparing the Planeshift Familiars (and other effects that lower the play cost of a spell) to coupons. They lower the final total cost of whatever it is you are buying. Recently I've started referring to state-based effects as 'couch potatoes.' They don't actually do anything as long something is happening. In other words while a spell is being announced or resolving they stay put. However when a commercial is on i.e. after a spell has resolved, they get up and get something to drink, or put a local enchantment that is no longer on a legal permanent in the graveyard. Just by reading the answers given by other people you can find / steal analogies to help explain the game.
Be confident in your abilities
In my opinion, outside of the working more tournaments, answering questions online is the absolute best method to gain confidence in your abilities and knowledge. By cruising a few bulletin boards and newsgroups in just one hour you can answer as many questions as you would over the course of a several rounds in a tournament. By applying your knowledge frequently you can't help but become more confident.
You are also more likely to be overtly appreciated by answering a question online. In a tournament setting, players often just want the answer so they can finish their game. Online you will often get thanked for your assistance. That can boost both your confidence and your self-esteem.
Even with all of the benefits of answering questions online it is obviously quite different from working an actual tournament. Here are a few things to watch out for when answering questions online.
At home on your computer you can have the Comprehensive Rules, Oracle, Floor Rules and Penalty Guidelines all open and ready to use. Odds are you will not have this so readily at hand in a tournament setting, especially if you are working the floor. Try not to look up too many answers. These documents are tools to help explain something you should already know. As in a tournament setting you should be able to answer a player's question without a whole lot of research. Use those documents to help explain your answer, not to help you come up with an answer. That doesn't mean that you should never do a bit of research, if you are uncertain as to the correct ruling feel free to look it up.
In a tournament you need to keep any ruling you give short and to the point. When answering online you can answer the question, give an analogy, provide a similar example that happened on a Pro Tour, compare it to how it would have worked before 6th edition rules and show the proper section of the comprehensive rules if you want. However in a tournament setting you will probably just give your answer and a brief explanation if necessary. You don't want get in the habit of over analyzing a rules interaction. In a tournament most players want a simple answer and that is it. If they want a more involved discussion they can wait until after the round or after the tournament. Additionally matches do have time limits, and most of the time in a match should be spent playing the game and not listening to a judge drone on.
When answering questions online you are not really a judge. You have no real authority. However stating that you are a judge in your response or in your signature does lend credence to what you say. Up until a few months ago I did not include the fact that I was a judge in my signature. If my answer is taken as correct it should be because it is and I backed up my ruling with evidence, and not just because a judge said it is so. I only include my judge status in my signature because so many people were asking for confirmation of my answers from a judge. Another thing to keep in mind is that even if you are not really a judge online, you are representing the DCI. Try to be as friendly and customer service oriented as you would be at a tournament.
One of the reasons I became a judge is because I do love this game. I enjoy playing it, but I also enjoy helping others play it. Answering questions online is not a real replacement for working tournaments on a regular basis, but it can help you learn how to best help others. By answering questions online you can help an enormous and diverse group all over the world play this game, and hopefully become a better judge in the process
If you are interested, here are the addresses of a few rules focused bulletin boards that I am aware of. (Keep in mind that in order to post on these boards you will most likely have to register.)
Wizards of the Coast
I'm not sure but it is probably the busiest Magic rules online bulletin board:
I may be a bit biased here, as I am a moderator of this board, but a good and fairly busy site.
And the Newsgroup:
You can read this Newsgroup here.