I agree with most of the other people. You've clearly played a lot of party-based RPGs before so I'm sure you can build a character. You can change quite a bit of your custom character once the game gets properly started (after the prologue), but once I've started a character it just didn't feel right to change them much.
Don't worry too much about exactly what to build because the game is quite forgiving in the easier modes. Don't look at too many guides unless you're actually stuck because it's much more fun to see the story fresh, at least the first time. Do use quicksave, because I think the autosaves are a bit too infrequent. Combat can be slow, and it's really annoying if everyone dies and you have to start again. Yes, you can save in combat or in conversation. Don't try too hard to avoid failure, because this game sometimes gives you interesting consequences for failing a roll.
Oh, and when you start picking up magic items, use them. If you've played D&D 5e you'll know about how you can only use 3 attuned magic items at once. BG3... doesn't really have that limit so you can have powerful magic items on any part of the body you can fit clothing or accessories on. I've got a really fun combo going on now with a lightning-based sorcerer with loads of different magic items to boost his lightning powers.
