Firstly, I am very excited to have had my Chef talk accepted to KCDC. It's my first talk given at a larger scale, outside of Cerner. I'm not new to the nerves and prep requirements of public speaking, however, internal to Cerner I've given a few talks with attendance at 500+.
So as I'm embarking on this, I wantedto share a couple resources that have been the most beneficial to me in the past.
First there's a general approach I credit to Michelle Brush. The short of it is "write a word-for-word script of what you want to tell the audience". This notion of drafting a blog post as the starting point of your talk has helped me enormously. It gives you a lot of room to cut from. When you start by drafting slides, it's harder to see what needs to be cut and what not. When you think of the entire body of words, and then extract a visual aid from that, it works really well, at least for me. She also mentions the stat that the average amount of time it takes to prepare an hour of content for a talk is about 30 hours. That seems high, but having done a small number of talks of that scale, it's been true so far. The number 30 hours might be low even, for the person who doesn't do it for a living.
Second resource is Zach Holman's speaking.io. He is hilarious, candid, and extremely knowledgeable about public speaking. And it's not general to public speaking, it's very much about the different hurdles and details around giving tech talks. I don't have much I can add, go read every page of this site, benefit, and feel happier for having done so even if you never give a talk.