People are turning to audio and visuals when it comes to technical subjects. However, you should consider doing an ebook first and turning it into an audiobook through a resource like Audible's ACX platform. You can hire a producer either through a royalty share program, so you don't have to shell out upfront cash, or you can do a pay-per-hour hire as well.
Now next, you’ll want to pick a WordPress theme from somewhere like ThemeForest, Elegant Themes or OptimizePress. This is the barebones design of your site, which you can then customize with your own branding, copy, and images. That being said, you don’t want to cheap out. It costs less than $100 to buy a theme that will make your website look professional (and you can upgrade to a completely custom design once you get the business going). You'll also need strong marketing tools to grow your website, like HubSpot's All-in-One Marketing plugin.
How much of your marketing strategy should be done online and which internet marketing elements you use depends on the nature of your business, your budget, your time, and your goals. Many small business owners do it all themselves in the beginning, but as their businesses grow, they begin to pay for services or outsource work to a virtual assistant that can help them with online marketing.
There are lots of Amazon affiliates in this space, mostly because it’s a strong hobby (i.e. passion) niche with tons of products. Which is good, since tons of these big stores are very general in nature, making it possible for big outdoors sites to possibly even pick one or two stores to recommend (this, in turn, might have other advantages, too, like negotiating better rates with those brands).
The topic you choose must have enough depth that you can create a lot of content for it. This is important for building an authoritative site, for search engine optimization, and most importantly, for the end user. If you don't have enough content about a topic, you're not going to be taken very seriously as an authority on the topic and it's unlikely you can convince someone to make a purchase from you.