Hey guys! So I've been a PC for about 9 years now, and aspiring DM for realistically most of that time.

What pieces of advice would you lend to someone who's dabbled in DM'ing but hasn't every really made the leap into running full campaigns, or creating his own for that matter?

At this point on the Campaign I'd like to make, I've got a lot of notes. Sort of general things (basic maps, points of interest) a few historical events, countries & their relationships, some cool NPC's and some basic ideas for what I would like to happen throughout the plot (I know, nothing ever goes according to plan.), with plenty of info to make the world keep running behind the scenes, and have events happen while the Players are out dungeoneering.

I guess my real question is two-fold:

Where do I go from here to turn these scraps into something resembling a playable campaign; Do you guys just start small & let your players kind of expand & elaborate on the world you've built; Do you have all the parts ready for PC's to play with?

And

How do you guys prep for a play session; What should I do specifically? (I've DM'd mostly one offs, so there was never too much going on plot related, or anything beyond Door Kickin')