I'll give you what I do. I assume that tech talk here means seminar and not class. For a class I do things differently. First, write down the goal of the talk. What should the audience know, be able to do, etc. after this talk? If it's more than three bullet points, it's time to start cutting. Remember, in a talk, everyone is at the mercy of your pacing. Any given audience member will probably space out for at least five minutes of an hour talk, and if you're at a conference or embedded in a workday, they're already overwhelmed with information.
Then sketch an outline of presenting that information, just a rough order of what to touch on. I find that I naturally outline so that each entry is about five minutes, but I don't know if that's just me or a common tendency.
Then I get a timer, stand up, and start talking to myself. I'll take an outline entry, and try to tell an imaginary audience about it. Typically I realize that I have some questions I need to answer for myself, or I run over five minutes. Think about how to drop stuff, look up what you need, note down what bits of verbiage came out that flowed well to reinforce them for yourself, and do it again. I often get frustrated after two or three times on one item, and go do another one, then come back to it and do it some more. During this whole process pretend the perfect slide to go with your text is up next to you so you can point.
After some cycles, this will converge. You will know what you want to say, and you will know what needs to be on the slides. Now set the timer for the full talk length and give the whole talk like this, still with pretend slides. You'll probably find places where you need transitional material, and it will probably run long despite the fact that the pieces add up to fit. Adjust. Do it again. This is also a good time to figure out and memorize the first couple sentences of each section, which will let you transition easily if you lose your place.
At this point you know your talk. Now go sketch your slides out on paper, and give your talk pointing to the paper. Once you think you have what you need figured out on paper, then go turn them into a PowerPoint, PDF, whatever.
Now practice it with the slides. Practice starting from a section using those memorized sentences. Memorize your sequence of outline items with those sentences attached.
Then do a run-through the day before. The day of, I spend five minutes thinking through my outline and section starting sentences, take a deep breath, and talk as inhumanly slow as you can. Even if you don't have stage fright (I don't), you will have adrenaline, and you need to slow down.
Then sketch an outline of presenting that information, just a rough order of what to touch on. I find that I naturally outline so that each entry is about five minutes, but I don't know if that's just me or a common tendency.
Then I get a timer, stand up, and start talking to myself. I'll take an outline entry, and try to tell an imaginary audience about it. Typically I realize that I have some questions I need to answer for myself, or I run over five minutes. Think about how to drop stuff, look up what you need, note down what bits of verbiage came out that flowed well to reinforce them for yourself, and do it again. I often get frustrated after two or three times on one item, and go do another one, then come back to it and do it some more. During this whole process pretend the perfect slide to go with your text is up next to you so you can point.
After some cycles, this will converge. You will know what you want to say, and you will know what needs to be on the slides. Now set the timer for the full talk length and give the whole talk like this, still with pretend slides. You'll probably find places where you need transitional material, and it will probably run long despite the fact that the pieces add up to fit. Adjust. Do it again. This is also a good time to figure out and memorize the first couple sentences of each section, which will let you transition easily if you lose your place.
At this point you know your talk. Now go sketch your slides out on paper, and give your talk pointing to the paper. Once you think you have what you need figured out on paper, then go turn them into a PowerPoint, PDF, whatever.
Now practice it with the slides. Practice starting from a section using those memorized sentences. Memorize your sequence of outline items with those sentences attached.
Then do a run-through the day before. The day of, I spend five minutes thinking through my outline and section starting sentences, take a deep breath, and talk as inhumanly slow as you can. Even if you don't have stage fright (I don't), you will have adrenaline, and you need to slow down.