Alright, both Baldur's Gate games have been on my to-do list for some time and I have decided to the plunge. I am a complete novice when it comes to IE DnD games though, do you guys have any general recommendations on how to play this game? Do this, don't do this etc.
I will keep Volothamp's guide as a reference while I'm playing though the games.
Be patient. If you're starting wtih Baldur's Gate 1, know that you will be very, very, very weak in the beginning.
Every fight will be an ordeal. Don't think of it as a game where you're fighting trash mobs and can just stomp through encounters until you get to a boss.
Going mage can be very tempting, but they are SUPER weak in early D&D (basically, most of Baldur's Gate 1). They will basically be able to throw out a handful of spells and then be done. By the time you reach Baldur's Gate 2 they become near gods, but you'll have to endure a hell of a lot to get there.
Try to always make sure you have a thief and a cleric with you. The thief for finding traps and unlocking doors/chests, and the cleric for healing up.
The only penalty for resting is that there will be a chance for a random enemy encounter waking you up. The chance for that is increased if you rest in an area where you previously had an enemy encounter. Other than that, there is no time limit so the days technically does not matter.
If this is your first time playing this stuff, don't even look at dual-classing, but multi-classing may be ok. Note that only humans can dual class, and only non-humans can multi-class. The major difference is that multi allows you full access to all the class abilities, albeit at a slower rate of growth while dual will have a period of locking away a class's abilities in addition to ending the growth of a class when you dual.
For the most straight-forward approach, go fighter. If you want some other useful abilities, I'd say cleric is a solid second choice in that they can wear heavy armor and still dish out damage while allowing access to some nice abilities.