When the SL came out, I scooped it up, hungry for something different. Well, two campaigns latter, and I decide to go back to the Forgotten Realms.
The first thing I do is build NPCs. I have notes on backgrounds, items, personalities, etc.., but I keep it a little vague so I can tie them into the players as friends, foes, mentors, allies, rivals, etc...
Now I'm waiting on the players to finish their characters. Once done, I'll decide where to set 'em up. It's one of the good things about using a world with as much detail as the FR in that I can pick a place very detailed and run material there or vague and run material there.
I make sure that the NPCs help keep the players moving by acting as guides and reminders, as well as making sure that when the players actually do go adventure, that they stay way back and let the players get the glory by doing the dirty work. Tends to work well and keeps the palyers moving and roleplaying at the same time.