The best possible starting build is a melee type. I honestly don't like playing melee anymore because it is just so easy.
The easiest devastating character is a male half ogre with raised in the circus background, who gets dex to 12 and 3 levels in melee (with maybe some dodge), then maxes out str, then maxes out dex, then finishes maxing melee and dodge skills.
This is because half ogres receive an amazing bonus to strength and +10% innate damage resistance. Melee fighters are incredibly favored in this game. Magic can do extremely well too, as can gunslingers and other types, but melee is by far the easiest to just become insanely overpowering.
In reality, if a newer player needed to start with the best easiest starting build, you should actually make a Half Orc Male with the background ran with the circus named Kor. From the intro shop, get a staff, and a rapier.
Naming him Kor is very important, because this combination of name/race/sex/background will make the chest at the crash site have very good starting items: Magic Platemail and a Charmed Helmet.
For starting points, put 1 into dex, 2 into melee, 1 into persuasion, and 1 into willpower. At level 2 get the Minor healing spell. With the good armor you have, you don't need to worry about dodge until later, so as you level up just get dex to 12, put 1 more point into melee skill (should have 3 total now) and then max out strength, then focus on maxing dex melee and dodge.
Half Orc is better for completely new players because it allows you to put 1 into persuasion without spending points to raise charisma first (which ogres have to do). This lets you convince the bridge thieves you are from the thieves guild and then you don't have to pay or fight them. It also means you only have to put 1 point in willpower before you can put 1 into minor healing, also unlike half ogres, and that makes things simpler early on.
It's important to know that when int is lower than 5 (like a starting half ogre) then you cannot use anything but dumbed down dialogue, which isn't a good way to go through the game for the first time. You will probably want to spend points to get it to 5. Also half-orcs have low beauty, which will make a lot of people hate you in conversation, and you'll usually have to apologize many times at the start of dialogue just to make people like you enough to really talk to you.
A good trick is also to put 2 into the electrician tech discipline, and craft 2 charged rings, which gets you a +4 dex for only 2 character points, as long as you wear the rings. You can find the parts in Shrouded Hills if you look hard enough, but they are also easily purchased in Tarant shops (for about 70g per ring total or something super cheap). Similarly, if you get the Agility of Fire spell or Strength of Earth spell for 1 point, you can raise your dex or str as long as you cast those spells before battle (but it's a hassle).
If you don't want the very best possible starting build, you could also make a wizard style male elf with sold your soul background and get the spell Harm from necromantic, which will rip through most weaker enemies.
This was ABSOLUTELY epic!! Thank you!! My half-orc Kor is having lots of fun. My first playthrough of the game, but I really don't have time in RL for a slow game like this, because I want to finish my BG2 replay as well, since the last time I played that was in 2000.
This works great! I would only add for newbies that you should not forget to APPRENTICE from NPCs around cities. For example even though you spend 3 pts in Melee, you actually still need to apprentice/master/expert in the skill because that makes you infinitely better. Getting apprentice in melee for example, gives you +5 speed. And that's only for 118 gp!