(As demonstrated tonight by Dr Tom Smith of Davas Ltd)
Start with a good opening slide:
This will help get the audience’s attention, if anyone turned up:
Explain clearly the theory behind your subject:
and reinforce your points, where possible, with some practical demonstrations.
Make them memorable.
Of course, if you chose the wrong career, say, accountancy, rather than firework manufacture and display, you may be at a slight disadvantage with some of these.