Use the outliner when typing a lot of text:

• Switch to the outline pane, located at the bottom left of PowerPoint, and type the title for your first slide.
• Press Enter, then press Tab to indent the next line under the title. PowerPoint automatically converts this new line into the first line of your slide's body text placeholder.
• Type the first line of the body text, then press Enter again to start a new line. If you want the new line to be indented, press Tab, or press Shift/Tab to "unindent" the text a level, just as you would if you were entering text on the slide itself.
• When you've finished entering the text for this slide, press Enter once more, then press Shift/Tab until you've "unindented" the new line as far as it will go. Notice that a slide icon now appears next to it. When you begin typing on this line, it will add a new slide to your presentation, and the text you type will become its title.
• Keep on typing until you've entered all the titles and bulleted text for your entire presentation. You'll notice that you never had to remove your fingers from the keyboard to mouse around on the screen.
• Don't worry if some of your slides aren't formatted quite correctly. It's much easier to fix the formatting in one pass through the presentation after you've entered all the text than it is to tweak the formatting on each slide as you enter it.