You absolutely need to have a solid content strategy at the foundation. I personally had a great experience getting guidance in our own strategy formation from Shelly Bowen at Pybop.com, as she helped me realize that I was thinking about our tactics before setting a vision and strategy. She described the content strategy as a foundation that allows you room to move, which was refreshing. I also recommend The Elements of Content Strategy by Erin Kissane and Content Strategy for the Web by Kristina Halvorson.
I really found it to be a reductive process more than anything, like peeling back layers of an onion, and getting clear on why your company exists. With the "why" in place, you can then move to the "how" and "what" and know that your approach aligns back to your vision and mission, and the bright shiny objects that don't jive with that can be set aside for now.
Without this framework in place, your efforts are going to be scattered and you are going to waste time and resources on content with no clear purpose. I think of a first person shooter game, in which you accidentally have your controls switched and you are aiming your gun up in the sky when you are trying to point it down, and firing shots in random directions just trying to figure out how to even know where you are moving, and then someone shoots you.
With a proper decision-making framework in place, you can find the highest impact opportunity (trust me, with patience and intentional focus, it will reveal itself to you in an "oh shit!" moment). Give it the focus it deserves to do it well, and then confidently move into the next area.
I'm happy to discuss more specifics on this. As the CEO/Cofounder of Column Five, we have been implementing successful content marketing campaigns for over five years, but to be honest, nothing taught me what it takes to really make an impact like the process of properly redefining our own content strategy over the past few months.