First thing is, you need a controlled evironment. Something you can keep the same, so no outside influences can interupt your test. A soundproof room for example. You could place a person in the room...
Experiments are used to test a hypothesis (idea). The first thing you need to do is work out what you want to demonstrate or show. After that there are so many millions of examples this question is...
The following steps would aid in the design of a good experiment:
Identify what you want to investigate (e.g. Does it hurt to touch a hot iron) Consider what should be in the experiment (e.g....