What’s the quickest, most easily repeatable way to die 100 times

There's an eHow article outlining one method (however you need a level 50 character to utilize it):

1. Bring one character up to level 50. That's as high as you can go, so your character will have all their abilities. Ideally, you'll want to level a character that has a powerful Area of Effect attack. Yue Ying, Sun Shang Xiang, Diao Chan and Zhen Ji all work well. Of course, the best is Lu Bu, since he has the highest stats of any character.

2. Train a pair of horses that have the Find Weapon ability. This isn't hard to get and if you've played the game for more than a couple hours, you've probably already got at least one. Make sure one of them is very fast, with a speed of 400+.

3. Take your level 50 character and whoever you want to power level to the Battle of He Fei Castle, Wei side. Make sure your level 50 character is set as Player 2. Set the difficulty to Hard or something higher in order to get the best results.

4. Have Player 1 ride around and attempt to prevent the enemy from taking any of the objectives. At a minimum, ride in circles so you don't die.

5. Have Player 2 (your uber character) ride down and attack Sun Quan as quickly as possible. He has a swarm of officers around him, so beware. If you manage to kill him quickly, you will both get a boatload of XP and some of the best weapons to be had!

The quickest way to complete all the achievements (assuming you have sufficient skill level) would be to do it like this:

• Complete the campaign on Brutal, this will give you all the mission achievements below that require you to do it on hard difficulty as well (though in all honesty I had to do it twice, once on hard (also my first play through) to get through everything and then again on Brutal just to get it done). Also I did one on normal and only did the required missions to get through the game for the "Hurry up it's Raid Night" Achievement.
• To get all the Armory related achievements, on your normal/rush play through, save up all your money, buy all of one tier up upgrades (which will then give you the achievement) then reload your game and buy another tier. Make sure you don't save as it will give you all your money back at the reload point.
• With the ladder achievements, play random. When you get a win with random, it will also count as the race you randomed as. So random race as Protoss when you start the game you will get credit for one win as random and one win as Protoss. This goes the same with the Co-op games vs. AI.
• All the other random ones like, "Kill a full medivac", "Regen 500 HP on a roach", get "50 kills with one unit" (I BC rushed for this one and sent SCVs to repair), will all come in time as you get each race.
• Same rules apply with the co-op ones because most of them are race related (beat it on Random, gives you credit for random and the race you played as). Also for the difficulty related ones, do them on insane and they will give you credit for all the lower difficulties. Beat it on Insane and get credit for Very Hard, Hard, and Medium.