As voted by the 2006-7 Sailors
(Actually, it's the top eleven, but who's counting?)
(Revised in 2013 to Reflect Contemporary LD)
11. Physiological management
Control of your body leads to control of your mind. Get the right amount of sleep & food at tournaments. Drink plenty of water all day long.
10. Having fun
You should be enjoying yourself. Everyone who has a winning record in this activity enjoys batting around ideas with like-minded individuals. A sense of your enjoyment will infuse everyone in your round, including your judges. Of course, you don't want to take it too far -- many judges have the same sense of humor as cheese pumpkins. So play it straight, but enjoy yourself. If you don't like debating, why aren't you on the chess team instead?
9. Simplicity of cases
This is an oldie that has gone out of style to some extent. The point was that the simpler your case is, the easier it is to understand, and the easier it is to understand, the better it will sound to the judge. Nowadays, a straightforward simple LD case is a very rare bird on the varsity level, but I think this rule still holds true for LDers starting out. Don't overcomplicate (yet). The best rule of thumb is, try your case on the youngest person in your household, down to about age 6. If they look at you like you've got beans in your brain, simplify it. Keep in mind too that the better you understand a resolution, the easier it is to explain it, and vice versa.
8. Speaking well
If you sound like your mouth is filled with month-old molasses, yet everything you say is intelligent, you will win some rounds. If you sound like a polished Shakespearean actor, with resonant tones that soothe the judgic ear, yet everything you say is idiotic, you will win even more rounds. If you sound good AND talk smart, you will dominate. Practice speaking exercises. Listen to the advice at meetings. Never underestimate oratorical skill.
7. Opponent adaptation
Adjust your style appropriately. Treat lesser opponents with respect. Treat stronger opponents with the understanding that anyone can be beat. Don't speed-talk against a slow talker. Getting good speaker points often depends on your keeping your cool in tough, unbalanced pairings, regardless of where you yourself are in the balance.
6. Fast flowing
Practice flowing from day one, and never attend a round without flowing it. Even practice rounds. You will simply continue to get better at it. Fast, accurate flowing will mean the difference in your toughest rounds. Learn all the different flow styles and use (or create) one that works best for you, not the one that works best for someone else.
If you act like you know what you're doing, you might actually convince your opponents and judges that you do, in fact, know what you're doing. It is easiest to act as if you know what you're doing, by the way, if, in reality, you do know what you're doing.
4. Fast thinking
You have to be able to think fast, both in CX and when prepping rebuttals. Preparation in advance of a round, and remembering the responses you've already developed -- rather than creating them on the spot -- is the best approach because it requires that you save your fast thinking for the unexpected, while using your memory for the predictable.
3. Time management
Use your all time in a round correctly. Your constructives should be timed perfectly. 1ARs should be half and half Aff and Neg (although some varsity think 1:30/1:30 + 1 for V/C analysis, overviews, underviews, middleviews, views of the lake from the cabin, the view from tab, a dim view of the proceedings as a whole). NRs should end with a minute or two of crystallization, while 2ARs should be all crystallization, or at least argumentation entirely of the nature of, "This is why I win the round." (2AR styles have changed dramatically over the years; the idea of continued line-by-line was unheard of once upon a time; now it's all the rage, even though there's not much point to it, unless you're closing up a loose end. The idea of writing the ballot for the judge will never grow old.) Use all your prep time, even if it's only to take a deep breath.
2. Judge adaptation
Since ballots come from judges, working with your judges is, at least according to the HHHS coach, who will always rank this as #1, the greatest key to success. With former debaters and younger coaches, you can confidently use a certain measure of speed and LD lingo (almost always -- you'll know the exceptions). With older folks and traditionalists, assume that they are rational people who would like you to be clear and simple in your analysis (see Simplicity, above). They'll also respond to knowledge and confidence, not to mention speaking well. They will be less accepting of speed. If you actually know the individual, that is, if you know the judge, you are best off, because you can -- and must -- adapt to what you know that judge likes. Keeping your own judge book of sorts, in which you evaluate folks who have judged you, compared to their published paradigms, is an excellent idea in a world of MJP.
There is no such thing as too much research. At the highest levels of debate, all debaters are roughly created equal skillwise; it's the work they do in advance that can make the difference. Contrariwise, if you don't know it, don't use it. Know what you know and avoid what you don't know. Of course, the more you know, the less you'll have to avoid!