The Dark Souls franchise can be a very unwelcoming host. Although all of the tools are there for success, not everyone has the patience to truck through all of the horrors that await, or cope with bundles of lost experience points. But fear not -- you can make it with some help.
[Warning: this guide contains light, non-story related spoilers regarding some of the early events in the game.]
In addition to the spoiler warning, I really have to start with this caveat: I strongly encourage you to play as much as possible without the use of any reference materials, as part of the allure of these games is to discover and conquer everything on your own. That said, I'd rather bring people into the game than push them away by leaving them to their own frustration, so here are some strategies to help take some of the edge off your frustration.
To set yourself up for success in Dark Souls II, forget everything you know about other action games. Your number one rule of thumb is "have patience." Always expect the unexpected, and know that something could spring out from a corner or the ceiling at any moment. Don't let yourself get trapped, look at your surroundings, and have at least one exit plan at all times. You really need to pay attention or you're going to be seeing the death screen all too often.
To help facilitate this notion, make sure if you're a shield-based character to almost always have your shield ready. It doesn't have to be up (that slows your stamina regeneration), but be ready to use it at all times. If you don't have a shield, keep your hand ready to dodge.
Leveling up in Dark Souls II is as simple as earning souls, which can be grabbed by defeating enemies, or crushing "soul items" that you pick up along the way. The latter comes in two varieties: regular soul consumables and boss souls. With normal items, feel free to save them (don't just use them willy-nilly), and use them when you need just enough to buy an item or level up.
Boss souls are a little trickier. Using them often results in a massive amount of souls to buy items or level up with, but they also serve a second purpose -- you can hand them over later in the game to an NPC to earn some of the best weapons or equipment possible. A sound rule of thumb is to save these souls to exchange for the really sweet gear, but it's totally possible to complete the game without picking up any of the unique items, so if you really need souls, pop a few.
Leveling up in Dark Souls II is also a bit different than in its predecessor, as you can no longer increase your stats from bonfires. Instead, you'll have to head back to the main town of Majula (found right after the tutorial area), and talk to the Emerald Herald NPC next to the town's main bonfire. It's very easy to miss her the first time you arrive, so make sure you talk to her immediately because she hands you an Estus Flask -- a healing item that renews every time you rest at a bonfire.
Another change is how death is handled. After you use your first Human Effigy item, you will become Human, which grants you the ability to summon players in the environment while retaining 100% of your health. Every time you die in Dark Souls II, you will lose a percentage of your total health bar all the way down to 50% (there's an item I'll talk about later that cuts this down a bit), so dying often really hurts your chances of beating some of the tougher enemies that can kill you with a single hit.
But don't be so hasty with your Human Effigy items! They're few and far between, and you may find yourself needing one before a really tough boss battle. As a rule of thumb, do not use a Human Effigy unless you've "tested out" a boss a few times and have learned its patterns. That way, you can go in at 100% health and take them down after you've mastered your plan of attack. Otherwise, you're just wasting Effigies. You'll also want to write down who sells Effigies. Seriously, write that down along with their locations.
What hasn't changed is how you approach your starting character class. For beginners, I would recommend the Soldier or the Sorcerer, as they tend to have the easiest time initially. However, it doesn't really matter what you choose as it's only a template. Dark Souls II still lets you customize every facet of your character, so outside of some starting stats the game picks for you, you'll have full control over your items, equipment, and statistics. If you don't want any "wasted stats" from the very start and want complete and utter control from step one, pick the Deprived class.
So let's take this step by step after you reach the Firekeeper's hut to help you ease into the first few areas. First -- walk through the door in front of you and tap that bonfire -- in Dark Souls II, every single bonfire is not only a spawn point, but a means of fast travel. You have the option of entering each mist door and doing the tutorial, or skipping it entirely by running straight down the middle of the path and entering Majula, the main hub world of Dark Souls II. Here you'll want to talk to the aforementioned Emerald Herald, and walk down the path near the ocean down the hill, back in the direction you came from. This is the Forest of the Fallen Giants, the first area you "should" enter at your level. As soon as you enter the open air, find the bonfire against the wall on the right and take a rest.
This area is relatively straightforward, and once you climb a tower on the one main path, you'll find another bonfire and an old NPC to buy things from. You have the option of purchasing a few things that may be useful to you (one Effigy, and a few Soul Gems perhaps), or going back to the Herald to level up. I suggest putting a few points into HP right off the bat to increase your survivability. Making your way down the ladder, you'll loop around to the left and unlock the door very close to your initial descent from the bonfire, go down the elevator, and fight your first boss. He's a relatively simple encounter; just make sure that you stay behind him at all costs, as his front-facing reach is extremely far, and can break your guard depending on your build. Watch out for his stomp (roll away at least once as soon as he raises his foot), and keep whaling away at his feet.
Once he's defeated, you have a few options, but I recommend heading back to Majula, leveling up, and heading down into the crypt-like structure in the exact opposite direction from the bonfire, leading you through a sewer and into a giant ruin-like city. Run immediately to the right before the giant knight and grab that bonfire. You can then run past the two large enemies or fight them, at which point you'll enter a giant structure. Left and right both lead to a boss fight, but you'll want to go left right away to grab the Ring of Binding at the very end -- one of the most useful items in the entire game in that it increases your maximum health to 75% rather than 50% when you die. From here, you have the option of taking either path and experimenting with both bosses. Do not be afraid to leave an area and come back -- there's no shame in leveling up and besting a hard boss later in the game.
So how about those other areas? Whenever you're comfortable, head back to town. See that giant pit in Majula? You can wait until later in the game for an NPC to build a ladder down there, or you could go into the Cat's house and buy the Cat Ring, which will allow you to survive when falling to the first plank. If you're wondering how to get through the area connected to town that has a stone maiden stuck at a door, you'll need a Fragrant Branch of Yore from a later boss in the game.
Now that you know how to access every branch from Majula, there are a few more things you need to know about. When you're talking to NPCs in Dark Souls II, exhaust every dialog option. Even if they start repeating themselves, try to talk to them at least two or three more times. One particular NPC will open up a required area of the game this way (hint: they're in Heide's Tower of Flame after the Dragonrider). Another bonus for talking to NPCs is that many of them will go back to Majula, so you don't have to hunt for them to find certain items.
One big NPC win is the old lady from the second Forest of the Fallen Giants bonfire. She sells limited effigies and large Soul Gems, but she'll sell you unlimited amounts of basic Soul Gems, which can really help you out in large boss battles when you run out of Estus Flasks. If you're having trouble in a certain area, you can brute force it by killing enemies 10 times, at which point they will not respawn. This is new to Dark Souls II, as is the ability to "run" up ladders by holding the run button (you can slide down them as well with the same motion). One more tip that will come in handy: If there are corrosive traps or environmental hazards around, take off all your clothes, weapons, and even rings so you won't break them.
That should be enough to get you started in the world of Dark Souls II. Just follow the above principles and by the time you clear the Forest of the Fallen Giants and pick up your handy Ring of Binding, you'll be good to go. Just remember -- have patience!