Training
You do not have to learn the hard way. There are training opportunities to get you started.
The Mathematical, Physical and Life-sciences division and Medical Sciences Division collaborate to offer public engagement training each year.
They also offer the Online Intro to Public Engagement with Research, which is a do it yourself online training that takes about 2 hours.
The Khan academy maintains an online course in storytelling.
There is buddy system in place in Oxford if you like more person help.
The STEM Ambassadors offer training when you become an ambassador.