My suggestion would be play BG1 +BG2 first by using the
BGT mod. I think the vanilla BG1 engine is very annoying and with BGT mod you can play BG1 with BG2 engine.
Then Planescape Torment. You might play this game first but I believe BG series is easier.
Then Icewind Dale series. More of the infinity engine.
I dont care about the rest really. ToEE is a good but buggy game. I couldnt finish it. Demon stone is more of an action game while Dragonshard is a strategy game. I found both clanky to play.
Also some quick tips about Baldur's gate,
STR 18/00 means STR 18/100 which is better than 18/99,
AC means Armor Class. Smaller the better.
Thac0 means to hit armor Class Zero. Smaller the better. If it is 20, that means you have to roll 20 (aka maximum) to be able to hit an opponent with an AC of 0.
While creating a character, you will roll ability scores. A total of 85-88 is good enough for any class.
Ability bonuses are not linear. There is no difference between 7 Constitution and 14 Constitution.
If you are not a fighter class (fighter, Ranger, Paladin), there is no need to go over 16 constitution.
Wizards need 18 intelligence. Clerics need 18 Wisdom. (ofcourse you may do whatever you want but this is highly recommended).
Also, High Dexterity is beneficial for ALL classes. Make it 18 if you can.
1 round is 6 seconds.
Playing as a mage on lower levels (as in BG1) can be insanely hard. Prepare to die often.
Q is quicksave. Use it often.
Often save in different slots. Just incase something goes wrong and you have to go back to previous save.
Have fun :)