Marketing a strategy is fundamentally no different than marketing any product. You've come up with a 'better mousetrap' that you think the world would be willing to pay for. However, it’s not enough to simply have a great strategy. The world will not beat a path to your door.
There are a few business models to maybe think about. Sell on your own. Sell through a marketplace (the Amazon model). Sell to a retailer (The Macy model).
Sell on your own. You would need to find and connect with your customers on your own. Maybe a website. Maybe friends and family. Word of mouth. This would be a lot of work (ie basically starting your own business). Might also run up against regulatory issues and need a brokers license to be selling stock advice?
Sell through a marketplace. There are a couple of sites out there that offer strategies a la cart. Take a look at Portfolio123 (https://www.portfolio123.com/app/r2g). QuantConnect seems to be headed in this direction too. One downside is these markets typically require you to use their platform. Not sure how much money you expect to make but Portfolio123 sellers (if they sell at all) make $10-50 / month.
Sell to a retailer. There are A LOT of financial advisors and planners out there (just do a Google search). Perhaps try to sell to them and then they can sell to their customers. This may get around any regulatory issues. They would also have a much better understanding of what customers actually want. Do they want low volatility? High returns? Low turnover?
Other than the few 'strategy sites' out there, there's no established avenue for an individual to profit from selling a strategy (that I'm aware of).
In the end, just like any product, it boils down to selling. As the saying goes 'it's 1% inspiration and 99% perspiration'. It's hard work convincing somebody to part with their hard earned money. Start the way you would think about any business. Who would be your customers? Who is the competition? Why would a customer choose my product over the competition? Why wouldn't they choose my product? How much would a customer pay for my product?
Just my 2 cents.