How to see all 16 endings...
	Rolling for the win...
	Various Achievements...

Here is a summary of choices you have to make to achieve all 16 endings.

Aryan Dies
Iorveth Path - Stennis killed.
Iorveth Path - Stennis spared.
Iorveth, Triss Path - Stennis killed.
Iorveth, Triss Path - Stennis spared.
Roche Path->Henselt killed.
Roche Path - Henselt spared.
Roche, Triss Path - Henselt killed.
Roche, Triss Path - Henselt spared.

Aryan Lives
Iorveth Path - Stennis killed.
Iorveth Path - Stennis spared.
Iorveth, Triss Path - Stennis killed.
Iorveth, Triss Path - Stennis spared.
Roche Path->Henselt killed.
Roche Path - Henselt spared.
Roche, Triss Path - Henselt killed.
Roche, Triss Path - Henselt spared.

An easy way to make Geralt faster early on is to get one of the first warrior path skills (unlocked at level 6-7 by putting points into the Witcher path). The warrior skill allows you to dodge further distances (level 1 is %100 and level 2 is %200). When your in wide open areas or even in a deserted part of a city, pull out Geralt's sword and start rolling. This will get you wherever you want to go much faster, because if you time it right you can roll without pausing in between rolls.

Note: If you try this near guards they may start to pursue you, just put your sword away as soon as they try and they will leave you alone.

Unlock Microsoft Gamerscore points by completing the following Achievements.

Ale Iacta Est	Complete chapter 2.
Apprentice	Use alchemy to brew five potions or oils.
Artful Dodger	Cut off a tentacle using the Kayran trap.
Avenger	Finish the game by killing Letho.
Backbone	Craft a suit of armor from elements of the Kayran's carapace.
Being Witcher George	Kill the dragon.
Black Ops	Sneak through the lower camp without raising the alarm.
Craftsman	Hire a craftsman to create an item.
Dragonheart	Spare or save Saskia.
Eagle Eye	Hit Count Etcheverry using the ballista.
Fat Man	Kill the Draug.
Focus	Perform three successful ripostes in a row.
Friend of Trolls	Spare all trolls in the game.
Gambler	Win an arm wrestling match, a dice poker game and a fist fight.
Gladiator	Defeat all opponents in the Kaedweni arena.
Great Potion!	Brew the ostmurk potion.
Guru	Achieve character level 35.
Heartbreaker	Seduce Ves.
Intimidator	Intimidate someone.
Journeyman	Achieve character level 10.
Kingmaker	Help Roche rescue Anais from the Kaedweni camp.
Librarian	Find all additional information about the insane asylum's history.
Madman	Finish the game while playing at the Insane difficulty level.
Man of the Shadows	Successfully sneak through Loredo's garden and find the component of the Kayran trap.
Master Alchemist	Acquire the Mutant ability.
Master of Magic	Acquire the Sense of Magic ability.
Miser	Collect 10000 orens.
Mutant!	Enhance abilities using mutagens at least five times.
Necromancer	Relive all of Auckes's memories in Dethmold's vision.
Oh My God! You Killed the Kayran! You Bastards!	Kill the Kayran.
Old Friends	Finish the game by sparing Letho.
Once Ain't Enough	Reach the Epilogue of the game.
Perfectionist	Kill 10 foes in a row without losing any Vitality.
Pest Control	Finish all quests involing the destruction of monster nests.
Poker!	Roll five-of-a-kind at dice poker.
Reasons of State	Stop Roche from killing Henselt.
Ricochet	Kill a foe by deflecting his own arrow at him.
Sensitive Guy	Save síle from dying in the unstable portal.
Spellbreaker	Help Iorveth find the dagger needed to free Saskia from the spell that holds her.
Swordmaster	Acquire the Combat Acumen ability.
Taster	Drink one potion.
The Butcher of Blaviken	Kill 500 foes.
The Fugitive	Finish the Prologue.
Threesome	Kill three foes at once by performing a group finisher.
To Aedirn!	Complete chapter 1.
To Be Continued...	Finish the game at any difficulty level.
Torn Asunder!	Kill more than one opponent using a single exploding bomb.
Tourist	Tour the camp with Zyvik.
Trollslayer	Kill all the trolls in the game.
Witch Hunter	Leave síle to die in the unstable portal.