As advice for new players i would share this:
* i would reccomend the knight as a starting class, high HP and a good shield makes the first boss very managable, and on top of that the knight is also a very eficient class to transfer into any other class because of low luck. luck isnt a usefull stat on 99% of the possible builds.
* If you wanna play a sorcerer, explore throughly, because one of the key-npc's to get sorceries early on is irreversibally missable. (or look him up on the wiki if you dont mind spoilers).
* if you wanna play miracles, it might also help to know that you can 'ruin your chances' with the relevent NPC. i dont wanna spoil anything here, but if you are going to play miracles you might want to look up this NPC on the wiki.
* there is no levelcap, but for PVP and COOP it helps if you stop leveling around 120-130 because of how matchmaking works. going beyond that will hurt your chances for matchmaking. (password matchmaking with friends doesnt suffer this problem, since you will get scaled down to the level of the host).
general advices on stats
* Vigor gives HP, you dont need to prioritize this stat, simply put a few points in when you feel like you are to squishy. 27 is the first soft cap and likeley enough for most PVE content, for endgame PVP you might want more.
* Attunement gives FP (magic points) and magic-attunement slots. most melee builds dont need much, but for a few utility spells having 14 or 18 (2 or 3 slots) is usually fine. Casters usually don't go above 30 (5 slots) - 33 (for the extra masgic points).
* Endurance gives stamina, simply put points in when you feel like you run out of stamina to quick. Generally melee needs more than caster, especially when relying on blocking (rather than rolling). beyonf 40 you wont get much more stamina, but usually you dont even need that much.
* Vitality gives extra equipment load, but also gives a lot of defense per point. most builds would take just enough to stay below 70% equipped:load since between 30 and 70% you will be a able to roll (medium). above 70% rolling becomes horrible, below 30% you will become really fast (realistically only obtainable in light armor). Taking extra vitality for the defense can be worth it if you are making a heavy armor - tanky build. Above 40 the defense you get will drop sharply though (Equipment load gained has no softcaps)
* Strength increases damage with weapons that have (good) strength scaling, also increases defense by a lot more than other stats (but not as much as vitality). Damage stats (STR, DEX, INT, FTH) are important stats at the start of the game. depending on what you are planning to do you probably wanna increase 1 or 2 of these stats early on. Strength generally works best on slow, heavy weapons. and if you are wielding a weapon in 2 hands, your strength will be multiplied by 1.5 (example; a weapon requires 15 strength? at 10 strength you can already use it as long as it is 2-handed). this 2 handing bonus is unique to strength. softcaps are at 40 and 60 (when one handing wepaons), in hybrid builds (like a dexterity-strength build) 40 is usually enough, 60 is generally what people go for in pure strength builds.
* Dexterity increases damage with faster, lighter weapons it has the same softcaps as strength. Bows, crossbows usually also scale well with DEX. a very polpular build (called 'quality build') gets equal amounts of strength and dex (40/40) which lets you play with the majority of the weapons in the game. Other then weapon damage gives a reduction to falling damage but this is generally no reason to spend points in dex. it also increases cast speed for casters which caps out at 40, which is usually to much an investment for pure caster-builds. Good to know: a ring exists that gives castspeed increase, with this ring casting speed caps out at 20DEX which might be worth considering.
* Intellect increases damage with sorceries and weapons that scale with INT. Pyromancies and dark spells scale with INT as well, but also need FTH to do well. 60 is the cap for pure builds, 40 is the cap for hybrids and pyromancers, 45 is the cap for dark-damage. at 50 INT you can use all spells in the game.
for other builds it might be worht taking a few point to have acces to some utility spells (10 for magic shield, 15 for hidden body and rapport (pyromancy)), do keep in mind that you will need attunement as well.
* Faith increases miracles and wepaons that scale with FTH. it shares the same (soft)caps with intellect. taking some point for utility might be worth it on other builds (15 for tears of denial, which is a very good spell). at 45 faith you can use all miracles.
* luck increases 'item find', which increases the drop chance for all items when killing enemies. this is generally not worth the investment. luck also increases status build up (bleed, posion) and can be worth taking if this is what you are going for, but these builds are usually a bit more complicated since other factors (like hollowing, weapon choice, infusion, bufftype) play large roles in how effective these builds play. I would advice against it unless you know what you are doing.
Other beginner tips:
Take your time on your first playtrough, explore well. this will be a huge help in succesive playtroughs. knowing were items, npc's and spells are found allows for much faster class-building. Also, a large portion of the game is optional and hidden very well. huge areas with multiple bosses are completely missable by failing to find something as trivial as an illusionary wall.
Get the DLC as well. Ashes of ariandel is a bit short but has a really good bossfight and some very cool weapons. Ringed city is extremly hard, much harder than the basegame, but its also very good. good bosses, awesome levels and more great wepaons and armors. Also ringed city gives acces to some of the best rings you can get in DS3.