First of all, thank you for being a Maker and not a Taker.
You heard about cool stuff and realized that, to get TechTalks, Workshops and more, you want to found a new chapter. Takers are people you will have to deal with all the time. These are the people that will register and than (sometimes) come to your meetings, eat your food, take the input from the talk and leave without contributing. Don't be mad at them, because they're a bit like the soil you're sow in your seed. Some of them will grow, become more active, ask questions next time and will end as speakers or part of your organization team or maybe even found their own chapter in their hometown.
That's the moment you will know that you did a good job.
So now, for those of you who never organized a UserGroup in their life and who might feel a bit uncertain about what to do, do not fear the uncertainty, it's part of the process. Shit im still almost wetting my pants before i start of an event. Especially when it is something that i have never done before. Take my first BarCamp, 350 attendees, five people in the Orgateam, i couldn't say one WORD when standing in front of all these people. And know, ffwd to 2011, ask the other Organizers that met me at IO or last years BootCamp before GDD in Munich - i am the loudest person that you've ever met (which im sorry for, it's just my way to deal with the uncertainty)
So be loud. If you want to practice, ask for five minutes at the next UG meeting of another group to introduce your new found GTUG. They won't bite and you can use the opportunity to learn how to speak in public. If you have the chance to take a course at your local school, on how to speak: use it! There's a reason why professional speakers, like politicians, are trained to speak. It simply makes you way more comfortable if someone told you what you are doing wrong, before you can do it wrong in public.
Also try to record your introductions and talks so you can watch them later.
To the organizing part: Read "Jono Bacons - Art of community managment". It's free, but if you like it, i highly recommend buying it, so Jono get's his cut. You can get the free (Creative Commons licensed) Version here: http://www.artofcommunityonline.org/get/
Also follow Jono
on Twitter, he's a pretty nice guy.
Take a look at the Wiki too - decades of Organizers (ok im lying, GTUG is only about 3 years old) have asked themselves the same questions that you have right now: