Since so many people like to do detailed roleplaying that is impossible to do in 4th edition and have characters that are a litle more believable than 4e's ridiculous overpoweredness (a fighter, *hitting* things with his sword; *snort* clearly inspired by WoW!).

So here is D&D 3.5X; a system designed for good roleplaying! Because I think we can all agree, it is the rigid codified rules of a system that allow people to roleplay, not actually roleplaying!

To play D&D 3.5X, you will at least need the Core 3.5 books, but more is helpful.

Initial Steps:

As DM choose a play style, campaign style, adventures, campaign theme and arc. Also, decide what characters your PCs will be playing, include important details like roleplaying habits and quirks. Make every possible character decision about them, from 1st through 20th. make the character you envision your player to be playing. Taking away having to think about their character will help make your PC concentrate more on issues at hand, they will thank you for it later. If you are comfortable with it, give your Player a list of acceptable feats, personalities and backstories. Really though, you should just decide everything, you are the decider after all.

Classes:

You should assign the PCs classes like Monk and Warlock, if you are running a high power game. A normal game though should use commoner, which isn't perfect since even that is too high powered. Really, you should create your own class that you should keep secret from the PCs and arbitrariily and capricious decide when someone succeeds or fails.

Skills:

If you are ok with it, allow the Players to pick skills, but ideally you should pick them.

Last: Have FUN!!!