For day-to-day presenting, there’s only two things to remember:
Next Slide: Use the SPACE bar on your keyboard.
Previous Slide: Press P (for Previous) on your keyboard.
You can also navigate around with the arrow keys on your keyboard, but hitting SPACE is much simpler!
Press F to show your presentation in full-screen mode.
Press Esc to stop the full-screen mode again.
Sometimes you want to focus your audience on something else than the slides.
Press . or b to turn the presentation black.
Discuss things out, then press the key again to return.