There's already tons of great content here for things like finding product-market fit and scaling your business. What I haven't seen much content on is things like best practices for setting up a new business.
With this I mean things like:
I know a lot of these topics will very based on what country and/or state you establish your business in, but I think it would be awesome to collect as many guides, tools, and/or resources that you all have found helpful in your experiences.
I would recommend speaking to a tax professional as soon as you can. Funny enough, they will have some insight into ALL of these questions, as their customers are all businesses. And if they don't, they can certainly make introductions to other entrepreneurs with similar businesses.
Being German, I can't give you much insight into the US system, but I can tell you that it is important to get this right. You can always start off using a personal bank account and claiming the income as your own. But with that comes liability, and you want that to be on the company, not your own personal finances.
And here is the thing: you can start one company for more than one project. Having a company to house all of your future projects is certainly better than not having one. I personally would do this very soon, particularly as you seem to have a product already.
There will be more than enough other stuff that you can react to as they come up, but this is an important foundation. And honestly, if you're ever looking at being acquired, having everything in order from the beginning is a clear sign of professionalism, too.
Stripe Atlas will handle most of this for you, so that could be a good option.
Thanks, Arvid! Really appreciate your reply, I will definitely consider creating a single company for all my projects - sounds like that could simplify things for me in the future.
I haven't used it personally (it didn't exist when I was getting started) but it sounds like everything you need would be handled by Strip Atlas: https://stripe.com/atlas
Whether you go with that or something else, I'd encourage you not to spend any more time on this than you absolutely have to. When it comes to product, marketing, sales, hiring, etc. the better you are at it, the more successful your business will be, so there's a good reason to want to read up and become an expert.
But for this stuff, my experience is that as long as you're meeting the basic requirements, there's virtually no benefit to being "good" at this stuff. That might change down the line if you raise money or end up with complicated finances, but for a typical bootstrapped business, it's fine to do the bare minimum here so you can get back to the stuff that matters.
worry about those later, build something first.
I do have something built! I am coming up quickly onto some of these things, so I am trying to get a good picture of what to expect and hopefully jump ahead on some things rather than just reacting as things come up (as I have a tendency to do..).