What advice would you give newcomers to Dark Souls 2 to prepare them for it without actually spoiling anything? Here's my contributions:

• You can kill NPCs.
• NPCs can kill each other offscreen. If one seems too hostile or suspicious, you may want to kill them first.
• Shields will save your life.
• You're not wary enough.

Stamina is used for blocking, dodging, running and attacking. If you don't have any you can't even use your flask to heal. The weight of your equipment greatly affects how fast it drains.

Dodge more, shields won't always save your life.

Know when to drop your shield. You need to keep your stamina regenerating as fast as possible during a fight.

TAKE IT SLOW

Don't fret over lost souls. There's always a way to get more. That being said, if you have a surplus of souls you should probably go ahead and use them instead of being risky.

Also, you should probably decide pretty quickly what kind of character you want and then start building your stats in that direction. Leveling up gets very expensive later on and having souls wasted in useless stats is annoying.

Shields are overrated, if you don't like blocking than don't listen to people on the internet.

Don't let the multiplayer scare you even on your first time. Don't just go through the game as a hollow, mix it up. Become Human and interact with people. Summoning and fighting.

Don't look at the numbers, which weapon feels more comfortable for you? A moveset that caters to you is more valuable than a modest increase in attack.

This a thousand times over. Also, upgrading gear is important, very important.

My Main Advise: Don't be afraid to start over, if you create a character and put a lot of skill points into one thing and find out you like something else better (for example focusing on strength and finding out you like spears that use dexterity or that you like to use magic). Go with how you like to play most in other action games and see if that works for you if not then try messing around with other styles you'd think you'd like with that character and, once you get a feel for it, start over knowing what you like/are good at. It may sound weird for such a hard game but with the knowledge of what the first part of the game is and a character made to play with your fighting style you'll rock the parts you did already in a fraction of the time, trust me, and it'll make the rest of the game that much easier.

Then just follow the advise the other duders mentioned.

What about the more nuanced aspects of Dark Souls? NPCs, purchasing items, upgrades, exploring, that stuff?

Could not agree more. Also, know what sort of weapon you want to use. Being comfortable with your weapon is a massively important part of Dark Souls. The game's already hard enough, you don't want to be wrestling with that too.

There is a lot to know when it comes to "nuances" in DS. For that reason, DS was the first game that didn't make me feel guilty about consulting FAQs and wikis. So, when it comes to things like which NPC has an item that you may want (like the Ring of Favor and Protection), or if you should upgrade weapons and armor (like @gatehouse said, get comfortable with weapons first) FAQs are your best friend.

All that said, one of the greatest things about Dark Souls is discovery and exploration and learning from your mistakes. I primarily used FAQs and wikis to determine which weapons, accessories and armor would be the best fit for me. Other than that I left most of the discovering to me. There are tons of random objects laying around the world that you can easily pass up if you don't have a FAQ, but unless you have Vinny levels of collectible OCD, you will probably find a way to survive. At least through your first play through.

Hope all of this makes sense.

Don't die.

Kill that guy

Git gud.

This, right here, is the best one. If you think you're going to blaze past areas, enemies and bosses then you're in for a rude awakening when they stomp you into oblivion.

Something else I wanted to mention:

Your starting class doesn't really matter as you will build your character to your liking anyways. However, a lot of people seem to agree that Pyromancer with the Master Key is a good way to start. While I never used pyromancy too much, the Master Key came in handy.

Also, if you plan on being a sword and board/knight, get the Drake Sword. It's a great early game weapon. Somewhere after ringing the first bell and before the second you'll want to look at a stronger weapon than Drake (which is not worth upgrading). After that the lightening spear helped me through Sen's Fortress. Then, the weapons will be to your preference. Personally, I really enjoyed using Black Knight weapons. Their move sets can take some getting used to, but they really made me feel like a beast.

@fraggingrights: This is a Dark Souls II thread. Although the "starting class doesn't really matter" could very well apply to DS2 as well as DS.

Too true. I just got too excited. Couldn't help myself!

With DS2 I believe the game suggests a class based off your in initial play style.

@fraggingrights: Ah that sounds neat. Can't wait to die in new ways in new places!

One thing I would add is that even when you're blocking you're not completely protected. Some enemies may jump at you (or fall on you) and hurt you, even when you're blocking. For these types of enemies looking around and being careful is much better than blocking.

Learn how stat scaling/weapon upgrades works. Don't be afraid to look stuff up.

I think many people don't realize at first that Dark Souls isn't a loot game. You aren't going to come across better and better gear upgrades as you play. Your starting weapon can get you through the whole game if upgraded. (Not to say you never get better gear, just that upgrading is much more important.)

Also, the game has a great community and a lot of experiencing Dark Souls is learning from what other people have figured out. Many people say "well I'm never ever going to look at a wiki," which is fine, but looking up basic info like what your stats mean or which area to go next is also a great way to play that doesn't spoil any surprises.

play demon souls and dark souls before entering the bloody arena that DS2 will be...with invasions being on even hollow, you better be prepared for frustration coming from other players even more than from mobs...