If you are looking for one important thing, the silver bullet, the undiscovered miracle of public speaking, it is:
For a first year expense of less than $50, you get regular experiences speaking in front of a group and getting the most valuable feedback you are likely to ever receive. It's like having a roomful of speaking tutors at your disposal. And you get to sit in the role of teacher and evaluator as well, tuning your critical listening and thinking skill further.
You'll get a book that will take you on a 10 lesson course in the fundamentals of public speaking - something that you will come back to time and time again.
There is no better avenue for learning public speaking.
Now that I've obviated this website, I guess I'll go home now. I just wish I could keep a good thing to myself....!