How can I improve my skills for public speaking?

Hi Dana, Hope you are well, I can give an answer that will change your life of public speaking skills and you will become the best speaker.
Depending on where you live, go to this website and check where is the local Toastmasters club is in your country, http://www.toastmasters.org/ This is where you should start, There are10 levels in the first manual (competent communicator), if you manage to reach level10, you will receive a certification from United States Toastmasters organization.
The club will assign a mentor as well as evaluator for you.
They will walk you through your journey to be a distinguished speaker.
Should you need further clarification, please don't hesitate to ask me.
Thank you for the excellent question.

Great question! There are a number of ways to improve your skills in Public speaking, but let me start with the basics.
First you need to be confident in yourself, this can be improved by understanding the topic/subject that you have been requested to talk about.
A great deal of research will not only make you more resourceful and prepared but it also gives you confidence on the subject and in yourself.
Secondly and most important, you need to understand your audience, this is because different audience will dictate your means of subject delivery.
By this you may want to consider, age, level of education, gender, culture etc.
these are just two of the basic ways you may improve your public speaking skills yet they are not exhaustive.