This is a strategic method used by players who start their round off as a Mystical student. M skills are very flexible in use, but generally offensively weak against the Red Dragon. An extra T or two can make all the difference in getting that quick first kill.
The Switching Method is simple: stay M until you reach level 8 (this is because level 8 is usually where everyone pauses to gain their experience and equipment to make the run to level 12). Then switch to Thief by going to the Dark Cloak Tavern, either randomly or with a horse. Hope to get a few T events (and definitely keep several gems on hand at all times) during the several days you're at this level. Then when you are ready to make the run for 12, or think you will be ready the next day or two, start looking again for that Dark Cloak Tavern.
Advantages to being a Thief while sitting at level 8 are well-known. You may rob the bank with any fairy you may catch, advancing your bank account toward that all-important upgrade price. On the days you begin as a Thief you will also have a bonus T skill, which you may need to kill a player a level above you. Pinches won't generally allow you to kill higher-level players, but in the running for 12, when everyone bunches up around levels 7, 8 and 9 on the first run up, that T can prove invaluable.
Tikel and Einherjar were the first to successfully use this method. The original method has its aberrations. The general rule of one of them is to switch to Mystical when leveling up and switch to Thief while staying at the level. Tikel is well known for using this method highly effectively, placing himself in excellent position for quick first DK's. Of course, the Random Number Generator doesn't always believe in letting the best-prepared players go first, alas.
HotShot was one of the first to propose starting the round as a Mystical skill user, but his preferred strategy was to stay Mystical all the way up to level 12 before switching to Thieving. He liked to acquire 16 M skills so that he could use Shatter after the dragon kill to advance quickly. This differs from the Switching method in that Switching focuses on getting Light Shield and 2 or more T uses for the first dragon, and conceding that Shatter is unlikely. The thought of Switchers is that Light Shield and Two T uses will usually get the job done just as well as Shatter.