Always start from the core. Always.
There's too much focus on the output.
If you don't know what the core is about, then there is no point in focusing on the output of that idea.
The core is about substance. It's about making your idea, product, or service meaningful and clear to whomever you envision will receive it.
How many times have I been in a meeting where the focus is about marketing strategy, without spending enough time on the brand and communication strategy...the "raison d'etre" of an idea or product.
"Why is it" important for your audience, "how is it" going to connect with people, and "what is it" about--these are key core questions that need to addressed, in order of importance, before considering a marketing strategy.
We live in an age of grand digital marketing opportunities. It is therefore not surprising that we get caught up with all the "shinny new" possibilities and glaze over the elemental core questions that need to be answered.
By starting from the core, we are able to harness a much greater connection with our fellow humans, which is good for us, and them. Human connection above all else.
Simon Sinek, in his famous "Start With the Why" Ted Talk brings this concept home. Thank you Mr. Sinek.