It's still very much early days, but we've done some tinkering around in Red Dead Online, and again after the update, and found a few ways to earn money relatively quickly, albeit still much slower than in single player. Here's a collection of our chosen ways to earn regular, Dollar-based cash in Red Dead Online - and thanks to posters such as tehdubya on the Red Dead Redemption subreddit for some helpful pointers, too.
Upwork: This website offers a great marketplace for selling just about any professional service. You don't need a merchant account, website of your own or anything else for that matter. All you need to do is be able to provide a high-quality service at a reasonable price. But be informed, you will have to compete with many others that are constantly bidding on open jobs. 
Stand in line for a new, long-awaited product that's about to launch in stores. Or wait in line for super hard-to-come-by concert tickets. Plenty of people are willing to pay the money for the product or the ticket, but they don't want to have to spend the time camping out in line. That's why you're there to do it for them. You can find gigs like this on sites like TaskRabbit.

If my piece of content is so unique and valuable around hiking backpack recommendations, that other reputable outdoor websites are willing to link to it and build the page’s authority, then I’d have a very real opportunity to rank high in organic search for these search terms (meaning, my page will come up first when someone searches for hiking backpacks).
Again, if your blog has a large reader base, then businesses may be interested in paying you to review their services or products. Not only will you get a free trial using whatever these businesses are selling, but you will also get a fee for writing them a review and posting it to your site. Paid reviews (and other paid and sponsored content) can be big money, so advertise this service on your contact page to generate business.

As an Instacart personal grocery shopper, you will actually be doing the grocery shopping yourself (so don’t crush anyone’s avocados!). Your compensation depends on several factors, like the average size of your orders and average number of miles driven per trip. You can also get tips in addition to the pay that comes directly from Instacart (most people report an average earnings rate of $15 per hour).
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