This seems a bit like the chicken and the egg. People tell me all the time how much they dread public speaking, and when I ask where and when they speak, they tell me they don't.
I understand being afraid, self-conscious, and all of that, but if you don't get practice, you will never get over your discomfort.
There's just no way around it. You can find every possible way to learn about public speaking without actually doing it: you can read books, buy audio CDs, take classes or get coaching, but unless you stand up in a room in front of people, you will never improve.
Start by preparing yourself to speak up in a meeting. Offer to facilitate a small committee at work, school or church, with people you're already comfortable with. Volunteer to give a short report. Introduce the new employee around the office.
What are some other ways you can dip your toes into the pool?
Apply what you've learned
If you've been collecting books and digital downloads, gathering information, reading free e-books, getting coached or trained, this is where you apply your learning. Without application, all the data you're saving in your brain means nothing.
Take those tips and tricks and just try one at a time. Work on one skill until you feel comfortable with it. Don't try to do everything all at once. Be gentle!
The important thing is to get started.
I'm not saying it's easy. It's really hard to challenge yourself to get outside your comfort zone. It's really hard to face your fears. But I'm going to be a hard-ass here. You just have to do it.
Find support through a mentor or supervisor, a coach, a Toastmasters group, or other colleagues, family or friends who are in the same boat. Use your support system to help you achieve each small goal.
Have a look at what Robert Crampton, writer for The Times Online in the UK, is doing proactively to get speaking practice.
You can do it! We're all here for you!