Praise the sun. Our Dark Souls Walkthrough provides tips for surviving the adventure, a guide to the entire world, and hints for slaying bosses.
Dark Souls no longer contains the Nexus of Demon's Souls. Instead, your safe havens are Bonfires placed around the world. These have several functions to help you on your journey, or may actually hinder your efforts.
Bonfires have three main functions just by resting at them: they will restore lost health, stamina and spells; upon death you will respawn at the last Bonfire you rested at; and most unfortunately, it will revive every non-boss enemy. Yes, the Bonfires are a double edged sword: you'll be restored to full, but in turn will have to battle through deadly opposition over again.
Additionally, resting at a Bonfire opens up a menu for various functions.
Leveling Up and Attuning Spells
The Bonfire's main function is to customize your character. Any stored Souls you have can be spent on various stats to level up your skills. You should save consumable Soul items--such as the Soul of an Undead--until you're ready to spend them on a level up. After all, you don't want to lose those unlocked Souls to a careless death.
You can also use the Bonfire to equip spells to any free Attunement Slots. In a change from Demon's Souls system, both Magic and Miracles in Dark Souls use the same slots. Another major change from Demon's is the removal of MP. Instead, each spell that is Attuned has a limited amount of casts. For example you can only use Heal five times before you will need to return to the Bonfire and replenish your supply.
However, you can Attune multiple scrolls to different slots for more casting. If you purchase two Heal spells, you may equip both for ten casts.
Humanity and Kindling
At the start of the adventure you will be a Hollow: an Undead that is slipping away into a mindless zombie state. You can very well play through the game in this state, although you have various restrictions regarding both single player and joining online. Hollow players have only the base drop rates and are easily hit by curses. Also you can only join other player's Worlds, but cannot act as a human host.
As you explore through the world and fight, you can gain Humanity points. When at a Bonefire you can spend one Humanity to restore yourself to Human form. As a Human you will gain increased drops, and this bonus is increased as you gather even more stored Humanity. Also, you can invite Hollow players into your game or invade other worlds.
Additionally, as a Human you can spend extra Humanity to Kindle a Bonefire. At a normal fire you can store up five Estus Flasks to recover lost health. However, Kindled Bonfires yield ten of these healing items. It is very wise to Kindle a nearby Bonefire before lurking into a strong monster's domain.
Revival and Reclaiming Souls
Dying is a part of Dark Souls. Upon death you will return to your last Bonefire in Hollow form with no Souls or Humanity. However, back where you died will be a blood stain holding your lost goods. If you can make it back to this spot you may recover your lost Souls and Humanity.
However, if you fail to touch this blood stain, those Souls and Humanity will be lost forever. Because of this, try to lure your enemies as close to a Bonfire as you can. This way, you'll have an easier time recovering your Souls, while crossing paths with the least amount of danger.