Follow the three Ps, and you'll be fine:

Prepare

First and foremost, make sure you know the materials. For some people, this means skimming the book; for others, this means reading every word and making note card of every single option, like a choose-your-own-adventure. I've been GMing for a while now, and I could probably skim the material and get enough information to run a session from it, but it wasn't always like that. When I first started, I had pages of notes that I had written, along with quotes for specific descriptions and short paragraphs on every NPC ("Farmer Williams: 'earthy' smell, dirty fingernails, muscular, quiet and calm"). If I froze up, I knew I could just read straight off the card. It wouldn't be "fancy", but at least my players wouldn't be stuck with me awkwardly flipping through a module. As you get better at figuring out what you use and what you only need as a reference, you'll end up doing less overall prep.

Practice

Your players are going to interact with NPCs, and honestly, that's my favorite part of role playing. Practice speaking as an NPC, snippets of conversation and ranting monologues alike. Taking out the trash? Act like you're a bored guard, muttering to himself about having duty in the rain. Commuting alone? Dialog with yourself as a drunken pick-pocket the surly barkeep. This lets you not only flesh out some characters, but it gives you practice doing really silly things, like terrible accents, without worry about people staring at you. And, next time you freeze up trying to figure out what that sullen guard says when the PCs ask a question, you can blurt out something like "I've been stuck in the rain for hours and you're asking me about [topic]? What do you take me for, a ruddy golem? Adventurers, pah, think they're center of the bloomin' universe!" without even thinking about it - which gives you a chance to actually figure out how to answer that question as your players are responding.

Play

RPGs aren't about stellar acting ability and slavish dedication to the rules (or at least they shouldn't be). They're about having fun - so don't forget that you're playing a game. It seems a lot of people forget that GMs are there to have fun, too. Don't be afraid to tell your players that you are nervous, or to push some of the responsibility off on others. Start your next game with the intention to have fun. If you forget something in the module, it's ok! Half the time your players won't even notice. Chances are, if you're having fun, your players are having fun too. Hopefully, lower stress can lessen your stage fright as well!

Follow the three Ps, and you'll be fine:

Prepare

First and foremost, make sure you know the materials. For some people, this means skimming the book; for others, this means reading every word and making note card of every single option, like a choose-your-own-adventure. I've been GMing for a while now, and I could probably skim the material and get enough information to run a session from it, but it wasn't always like that. When I first started, I had pages of notes that I had written, along with quotes for specific descriptions and short paragraphs on every NPC ("Farmer Williams: 'earthy' smell, dirty fingernails, muscular, quiet and calm"). If I froze up, I knew I could just read straight off the card. It wouldn't be "fancy", but at least my players wouldn't be stuck with me awkwardly flipping through a module. As you get better at figuring out what you use and what you only need as a reference, you'll end up doing less overall prep.

Practice

Your players are going to interact with NPCs, and honestly, that's my favorite part of role playing. Practice speaking as an NPC, snippets of conversation and ranting monologues alike. Taking out the trash? Act like you're a bored guard, muttering to himself about having duty in the rain. Commuting alone? Dialog with yourself as a drunken pick-pocket the surly barkeep. This lets you not only flesh out some characters, but it gives you practice doing really silly things, like terrible accents, without worry about people staring at you. And, next time you freeze up trying to figure out what that sullen guard says when the PCs ask a question, you can blurt out something like "I've been stuck in the rain for hours and you're asking me about [topic]? What do you take me for, a ruddy golem? Adventurers, pah, think they're center of the bloomin' universe!" without even thinking about it - which gives you a chance to actually figure out how to answer that question as your players are responding.

Play

RPGs aren't about stellar acting ability and slavish dedication to the rules (or at least they shouldn't be). They're about having fun - so don't forget that you're playing a game. It seems a lot of people forget that GMs are there to have fun, too. Don't be afraid to tell your players that you are nervous, or to push some of the responsibility off on others. Start your next game with the intention to have fun. If you forget something in the module, it's ok! Half the time your players won't even notice. Chances are, if you're having fun, your players are having fun too. Hopefully, lower stress can lessen your stage fright as well!