For new DMs both new and old the DM-Friendly module list on Neverwinter Vault is a good place to look for an adventure to run. In that list, I can personally recommend the following as being appropriate starter mods. Other comments and suggestions are welcome.
JHR1: The Vethboro Dragon was the module I ran (a whiillle back...) for my DM 101 certification game on the old NWC. It's small enough to be manageable for a single rookie DM, large enough to be meaningful, and a good mix of classic adventure and slightly whimsical humor. (Module author Jason Robinson was also a longtime DMFI contributor and website host, I virtually met him a few years after playing the mod.)
My own Amee Pass (recently released for NWN:EE) was playtested at the new NWC and is a simple, classic-style introductory D&D adventure with comprehensive DM notes. It was designed to be accessible to new DMs and for a new party of level 1 characters.
Muddles in Milton is a "soundstage" mod with no scripted plot, rather being a pre-built setting with a number of lovingly created NPCs and locations. The DM documentation of the in-game resources is top-notch as well.
If you like the Ravenloft setting, Poetic Colossus' A Requiem for Jander is another high-quality DM-friendly module that should deliver a powerful experience. The DM notes are very good and some extra preparation for the setting (if you need it) and how the party might go off track is recommended.
Lazybones' various modules, which can be found in the DM-friendly list, were also favorites for newer NWC DMs.