The best way to avoid this is proactively asking the right questions. Ask about resource support. Ask about historic roadblocks. Ask to be introduced to other players who otherwise hide behind an email here and there. Ask about the company's temperature regarding a bigger SEO strategy vs. short, quick-hit campaigns. Don't be your own biggest obstacle — I've never heard of anyone getting angry about over-communication unless it paralyzes progress.
Lastly, it's important to remember that paralysis by over-thinking is a real issue some struggle with. There's no pill for it (yet). Predicting perfection is a fool's errand. Get as close as you can within a reasonable timeframe, and prepare for future iteration. If you're traveling through your plan and determine a soft spot at any time, simply pivot. It's many hours of upfront work to get your strategy built, but it's not too hard to tweak as you go.