EOG is a great place to start, though for a custom, I feel like I’m the guy who always keeps answering with “it depends…” but, it depends lol.
What kind of ecom activities?
Dropshipping?
Creating your own products?
Print on demand?
Creating a course to sell?
Marketplace arbitrage?
While there’s definitely overlap, each one involves a different set of skills and actions… some require detailed analysis up front, others require design work or creativity… others require writing/recording/editing, and most will involve writing copy, for a sales page or an ad. Depending on how hands-on you are, maybe some website design and/or coding work could be involved.
You don’t need to share any details about what your project is, just think about the kinds of tasks that are involved with what you specifically want to do… that will help you pick specific modules.