@Zeta Dragoon You seem intimidated by the game; don't be. The first levels might be rough, sure, but you'll eventually find yourself overpowered as the game progresses, especially if you're even half-thorough in your exploration. Like you, I died a lot in Stormveil castle, but after completing Limgrave, Liurnia, Caelid and the underground stuff, it felt like playing a different game. I even went and killed Mohg, an endgame boss, even though I was still in Altus Plateau (the place after Liurnia); that's how overpowered you end up after doing everything in the game's early areas.
For skill points, make sure you level your vigor (up to 40) and put points/gear into increasing stamina, stamina regen and carry weight so you can wear decent armor (Radahn's set is excellent). You can find a phys reduction talisman in Caelid, at the bottom of Bestial Sanctum, and the Erdtree's Favour talisman in Fringefolk Hero's grave. You can get those right now (they're not guarded by bosses), and you will also find upgrades to them down the line.
Regarding the quests, stressing over them really isn't worth it, and will take away from your enjoyment of the game. Seriously, trying to get everything in 1 playthrough is a fool's errand, and will frustrate you greatly (I should know, I've done it). Besides, their rewards are usually items you won't even use, and you'll complete most of them without even trying anyway. The one quest you should definitely do is Ranni's; you can read up on it after you beat Radahn.
As for weapons, I like switching and trying new ones, but since you mentioned it, the Golden Halberd is a fine choice. Beautiful pierce/slash moveset, good range, big damage, great on horseback. Only drawback is you can't switch out its ash of war (still, Golden Vow is pretty good for bosses). It will easily carry you to the end of the game, unless you eventually opt for one of the more "broken" weapons like Rivers of Blood. Keep in mind, you will be able to respec after beating the magic academy, so you can always fool around with different builds. Oh, and make sure to keep a strike-type weapon upgraded as well, to use against hardened/stone enemies in catacombs and elsewhere who are resistant to other dmg types.
One last piece of advice: buy Margit's shackle from Patches, and use it when you suspect there might be illusory walls around - it dispels them. It also has a huge range, so if you use it once in a dungeon, it will probably clear all fake walls in it. For my playstyle, this may very well be the best item in the game, as I always think everything looks suspicious and I end up attacking walls more than enemies
