Your best starting choice will be Knight class with Black Firebombs as burial gift, which you can use to kill the First boss easier. While leveling up you will get native info about your stats, personally I recommend pumping Vigor first and Endurance second. When you think you have enough of those, you may wanna start leveling up Strenght or Dexterity for damage. Character stats and your build are most important, thats why i would also recommend reading a full guide made by a good friend of mine.

When first spawn in the game, be sure to go to the settings - input device - key bindings. Check all the actions available there and try to perform every action a few times to make sure everything is binded well enough for you to use. While in the first area, try performing different running and jumping attacks with your first weapon to see what you are capable of.

Open your Equipment menu and check Weight Ratio at top right. Always keep it below 70% by changing your equipped gear and leveling Vitality, but remember that anything below 70% is good. You have 3 weapon slots for each hand, 4 armor and 4 ring slots, which are counted in your Weight Ratio, but things you carry in your bag are not. You can also bind usable items there or place some of them in system menu quick slots. The game can be beaten with the very first weapon you get when spawning the first time, but it is recommended to find something that suits you best. Do not forget that weapons can also be infused and reinforced at the blacksmith.

Dark Souls Inventory is also your journal. Its lore is written on every item you get in this game, but what's even more important, there is a "Key Items" tab. When you get a key item, bother to read its details to get crucial information about the game.

Going through the game can be frustrating if you are new to it. There are no directions, quest marks or map you can use to guide you on your way. It is recommended to try and discover everything on your own, but if you are looking for something to guide you through the game, use the Playthrough Checklist[zkjellberg.github.io]: or Playthrough Videos

A good source of any info available for Dark Souls 3 is Dark Souls 3 Wiki[darksouls3.wiki.fextralife.com].
Warning: does contain spoilers.

Lighting a bonfire means gaining access to a new area and new spawn/fast travel point. Always remember where did you came from and where did you go. At every bonfire check if there are some closed doors or elevators that are locked. If there are, it means they can be unlocked from the other side to create a shortcut, that will give you an easier route to the boss or the next area.

Most NPCs in this game are not crucial to it, apart from the Firekeeper, Shrine Handmaiden and the Blacksmith, who are and will remain at the Firelink Shrine. Other NPCs and their quest lines can be hidden or difficult to do on your own without reading the guides, such as Playthrough Checklist linked earlier, but since they are not essential to the game, you will still be able to finish the game with no additional troubles.

Enemies can be divided into two big categories: those who respawn and those who don't. Usually the strongest enemies (bosses included) do not respawn and can only be killed once. Its pretty common for them to drop unique loot that can't be obtained otherwise. Respawning enemies can also drop unique loot on ther first death, but from there you will only get rare drops of other items.

Upon death, bosses drop their souls, which later can be transformed into powerful weapons, rings or spells at an NPC called Ludleth, sitting on one of the thrones in the firelink shrine. It is common for bosses to guard a path to the next area or at least drop a key item that guides you to a new location, so if you are stuck with your progress, try going through the last killed bosses bonfires and looking for a new path from their areas or through your key items inventory tab.

There are lots of secrets in this game, including hidden areas and bosses, and even what's not hidden can easily be missed by you on your first playthrough, it is pretty normal and the game is designed to be beatable while not discovering them at all. Still, pay attention to your surroundings and look for player signs, hidden paths, illusory walls or loot.

DS3 Multiplayer starts when another player gets summoned in other player's world as a phantom, much like some NPCs can be summoned in your world to help you with bosses. Players can help you with cleaning the area or killing an enemy, such as boss, too. You can enter the summoning mode that allowes you to see summoning signs by using an "Ember". By default, you can only see the signs of players around your level (aka soul level), but setting a password in Network menu allowes you to summon anyone who uses the same password. Entering summoning mode makes you vulnerable to PvP invasions and summoning phantoms puts you at even higher risk of one.

While you are in the summoning mode, you can be invaded by people and NPCs who spawn in your world as enemy phantoms. Some players might come out as friendly, but threat everyone as a hostile unless proven otherwise. There is no way to be safe from that apart from playing in offline mode or without using an ember, which means playing the game solo. The only thing etiquette suggest is refusing to fight a player invader by performing some peacefull gesture. Perhaps in this case it will not kill you. Obviously, it does not work with NPCs, and when it does not work, you have to fight. Do not be discouraged, it is pretty normal to lose up to 100% fights to the invaders while being new to this game.

The last thing to mention, this game does allow trading of most items and common souls, but not the key items, materials, boss souls and some other things. Trading is basically going into your inventory and "leaving" an item on the ground to be picked up by someone else. It is very recommended not to abuse the trading power, since that will alter the game experience, but in certain cases (like if you are to farm some enemies to get souls or some particular weapons or items from them), maybe it is better to just ask for souls or that particular item you need to be given to you via trade for time saving purposes. Be aware that you cannot see any equipment that is reinforced higher than your current max reinforced level, so if you dont have a +10 weapon, you will not be able to see +10 weapons dropped by other players.

In my personal opinion, one should start a "blind playthrough" with no help from others, no summons, or even offline, killing bosses on his own and without info from wiki or playthroughs unless stuck for real, and even at that point it will be most safe to just ask your experienced friend, "where should i go after killing X ?". But that is just my personal opinion, and whatever people tell you, do what you think is best and don't be discouraged by other people opinions. Enjoy DS3 the way you want to enjoy it.