You need to know whom you're selling. How can you create content without knowing whom you're targeting? I see too many people state they are content creators, even Creative Directors(!) creating beautiful, highly polished pieces of art. Not content. And especially not designed content.
Fully understanding the audience, your target market, is the first step – without this, you make no progress!
Now you know what your audience looks like, you can have a ton of fun imagining what they would say if you told them about your product or service. It might be "I'm not at home for much of the day, so the product has got to accessible when I need it, and easy to use too!" Now you have these you can then start to shape your message(s). But rather than a message, let's call it a hook.
How can you write copy, design images, create animations, draw infographics and film videos that will answer that challenge? "Stuck for time? Use the PRODUCT for your needs. It's easy. And with 24/7 support, you'll feel confident you can manage your needs at the time that suits you" – or something like that.
Measuring this isn't as tricky as you may think.
If you create several manageable amounts of personas, then create multiple ads/content designed to convert and see which works best – this is essentially A/B testing. Which one worked the best, what was the conversion rate? Did that content generate sales, proved through active link tracking.
Getting your personas to work is the second step to making your content strategy work. The first step is creating them!