"Write how you speak"
Have you heard this common advice?
It's well known and repeated in copywriting circles, but it's not good advice. Well, it's not good long-term copywriting advice. There's a subtly different but significant in impact tip that you should follow instead.
Write how your ideal customer speaks, not you
You should sound like your ideal customer, not yourself.
I'm a 35 year old white man originally from the UK with certain hobbies and interests. I use different words, phrases and even grammar than other people. If I don't learn their ways of speaking, I won't communicate effectively with them.
Your ideal customer wants to hear themselves when they read your copy.
So why do people say write as you speak?
Writing as you speak isn't bad advice.
If you follow it, you'll certainly come across better than if you tried to write an academic essay on a topic (unless you're writing to academics!). And it can help correct some common copywriting issues like
using the passive voice
using too much jargon
burying key information
But it doesn't address everything (when people speak, they tend to use more vague vocabulary and modifiers like very, really, etc.).
The main reason this tip is repeated is the people who repeat this tend to sell to people like them. So when they write like they speak, they are writing like their ideal customers speaks.
Learn how your ideal customer speaks
Writing like you speak is often a good first step, but make sure you consume yourself in your ideal customers world.
learn what topics they talk about,
how they describe their problems,
what cultural references they make
Then you can write like they speak, not like yourself.