Presentation Design

I'm looking to get involved in presentation design, public speaking consulting etc. and wondered if anyone could give me any advice.

Any software I should know how to use, other than logo design software (if you even consider this necessary). Obviously PowerPoint and Keynote are a given!

I want to know how is the best way to start getting some experience in this, as I've only worked on my own presentations before. I'm prepared to work for free to build up my portfolio, but I don't know where to find work.

Thanks for any advice you can offer!