Before you embark on your quest, you should know that there are certain events in the game that don't necessarily fit into a linear flow; some quests can occur on multiple planets, while there are also mini-games that can be played anywhere. If you come across an event that isn't covered in the main walkthrough, you'll want to refer to the Galaxy Side Quests section; if you want tips on a minigame, then you'll need to check the Minigames and Items section.
Very few console role-playing games give you much freedom over your character's disposition towards other people, or the game world itself. KOTOR, on the other hand, allows you to choose freely between "good" actions (which correspond to the Light side) and "evil" actions (which align the character with the Dark side of the Force). As your character makes more decisions that involve moral or ethical concerns, you might find that your other party members begin to react to you differently, or that your character's physical appearance begins to change.
This isn't merely a cosmetic affectation, though: the game's design relies upon you making decisions based on how you think your character would respond to a situation. (That's why it's called a role-playing game, after all.) Any one of these decisions will result in a small shift in alignment, towards either the Light side or Dark side of the Force; this alignment will affect such things as the cost of your Force powers, what equipment you can use, and, most importantly, how the ending of the game plays itself out.
In keeping with the spirit of Star Wars, KOTOR is designed so that walking the straight-and-very-narrow path of the Light side is more difficult than simply indulging all of your evil whims and sinking into the Dark side of the Force. Players who intend to become Dark Jedi will have a much easier time in the game, if only because conflict resolution is reduced to picking the conversation options that will most quickly lead to bloodshed. Dark Jedi will find themselves with more credits and more loot than their Light Jedi counterparts.
Light Jedi, on the other hand, will often find themselves bending over backwards to adhere to the Jedi Code. Among other things, the important gameplay aspect of the Light side is that the ends never justify the means, which can be interpreted as a statement of non-violence; the Light side simply doesn't permit you to kill someone without provocation, even if the greater good is served in the end.
Light side characters, in short, will need to:
And so on and so forth. To put it bluntly, being good in KOTOR, or, at least, being a good Jedi, is hard.
Simply because it is easier to be bad than good, this walk-through, for the most part, is intended to help Light side characters stick to the path of the righteous, since the developers have made it so difficult to do so. Dark side characters are not neglected; whenever the game branches off to allow Dark side characters a separate solution to a problem, that solution is mentioned, even if that solution is, nine times out of ten, as simple as starting a fight and winning. The Dark side's conversation options are often glaringly obvious; if you consistently choose to be avaricious, insulting, and downright violent, then you'll find yourself feeling the hate flow through you soon enough.