Aspects:

• The Samurai is obedient to his lord.
• It is a Samurai's right to protest against bad judgements or orders from his lord, and death is the final protest a Samurai can make.
• The Samurai is ready to die at any time.
• There is no such thing as failure, only death or success.
• To die in the service of one's lord is the greatest service a Samurai can render.
• No dishonor can go unavenged.
• Dishonor to lord or family is also dishonor to the Samurai.
• Mercy is not due the enemy.
• All debts, both vengeance and gratitude, are repaid.
• Cowardice is dishonorable.

Needless to say a Samurai PC needs a lord, although this may also be a western noble this is most likely an eastern daimyo. Samurai gain honor points for deeds they make much like questors do, but need to advance their honor rank in addition to any standard requirements for gaining a circle, as a gift their training is paid for by their daimyo (lord).
Consult page 90 in the Earthdawn Companion for details on Honor (devotion) Points.
Like Questors they can make minor, major or zealous actions all of them linked to the Bushido, so following orders to the point is a minor (you have to do that anyway) act of honor, bringing fortune and good luck to family and daimyo is a major act of honor and saving the daimyo is a zealous one. Note that the amount of honor points is up to the GM, but should be at least twice of what is listed in the book.
Failure, well failure to follow orders or smth. similar cause you to lose twice the amount you would have gained from your total, what (?) you lose one rank ? Well, then you've got two options (for your character):

1. Commit Sepuku; very simple just slit your guts open and ask your best friend to chop your head of before you show any emotional reaction on your face. (You've got to write a Haiku before that - on rice-paper if you please)
2. GO ....

RONIN

A Ronin is a Samurai with no Honor and as such is free to do as he pleases. Sounds nice, sure !
You lose all honor points, you gain no free training, no Samurai will teach you, your Ghostmaster won't appear, people spit at you and the only work you find is fighting in the front row of some sadistic, cruel daimyo for a cup of rice a day.
Still sounds nice - well, it's your choice, but chose wisely.

P.S. Otherwise a Ronin is treated as a Samurai in every way, note that a Ronin can not even summon a Ronin Ghostmaster, unless he can rebuild the Ghostmaster's reputation (=honor points).

Fed up with being a Ronin ? Not as cool as the movie ?
As a Ronin you can begin to rebuild your honor points from the start, which means that eventually you might be able to regain your position and might gain Samurai status again.
Did I forget to mention that the honor points you would gain being a Samurai are halved ?

Have Fun playing -- Jochen