First of all, im sorry you have catched the Diablo Flu... one day we will sit down in a circle and introduce ourselves and everyone will say "Hello".
Until that sad day comes there is a few good things to know...
* In options, select/check "Elective Mode" since it will make you able to mix any skills you want and not restricted to certian skills on one button.
*This is just me but i have moved my 1234 skills to ASDF because if you hold SHIFT you will stand in place and attack, when i had it on 1234 my hand kinda died after awhile... pinky on shift and the rest on ASDF... and Q (for potion) when needed, felt most natural imo.
*Difficulty, should i go Normal or just grind Torment 1-6?
Here is the thing, with the new Loot 2.0 as its called legendarys drop way more, before the patch i put 75+ hours before my first legendary dropped and had to wait 75+ more for the next, note that i had +300% Magic Find at the point... doesnt take a geniuos to figure out pre 2.0 was broken.
When you play Normal through Master the same loot drops since now it scales to your lvl, if you go Torment besides the + in Gold, Experience and Shards ONLY the monster drops matter.
Some stuff only drops on Torment ofcourse but only from bosses and normal mobs, chests is basicly a "world drop" and has it own loot table wich is NOT affected by difficulty.
Jeeez, hope i made sense there...
* Jewellry, they kinda f*cked this thing up with the expansion... once you can get the lvl 70 Marquise versions, dont be afriad to sell the old crap since it has no use and is just a hassle to lvl... do the math on what you need for a Marquise from the ground and put that on how often Marquise drops, not very hard eh?
*Blacksmithing might seem like a big huh? and it is on your first playthrough but it sure can sugar your alts and also you will find some cool recipes.
Besides that, cmon... you helped him kill his wife ffs, you need to keep him busy.
* Diablo is a multiplayer game but if you approach it as only that you will miss your followers story wich is actually pretty great in itself.
They all have their separate quest/storyline and you will miss the "mood" of them all if you just burn through everything in a group, there are TONS of dialogue/comments when you play through the game from all three followers and most of it is lore of the world.
I recommend to play through the story mode atleast three times with every character to get everything, also... if you play through it with the Scoundrel you will laugh your ass off, them comments.
* Some skills might seem like shit and yes, some are in itself but later in the game you will get the ability to swap ONE skill to whatever you want and that suddenly turns the tables on some builds.
Point is, dont knock off a new skill because you can get a thingy with a +10% to whatever it does.
A start atleast, feel free to ask anything... if i cant answer i will find the answer.
Oooooh, dont miss to check EVERYTHING, logs, corpses and so on... there are secrets everywhere and certian loot only drops from the enviroment.