Welcome! I'm fairly new myself, but almost finished a play through as a Warrior. I'm intentionally taking a long time, finishing everything, and basically dragging it out because whatever I do next won't be as fun.
I've only played as a warrior (1H + shield), so I can't speak to best classes or builds, but I'll pass on a key thing I missed early on (most of the game is self explanatory or nicely guided with occasional tutorial style feedback):
Throughout the game you run into many randomly generated adventurers that will join you for a fee, and last until they croak. But (and this is what I missed for a while) there are three story line relevant NPCs that will also offer to join you, and they can become permanent "Companions" (official game term) that will level up, be equipped by you, not die (they're temporarily incapacitated when they hit zero HPs), and be available to re-join you later if you dismiss them at any time. So keep an eye out for anyone that actually interacts with you and / or has quests to offer, and then is willing to join you.
Have fun!