Before you start building your SaaS, there's a few important things you should do first.
1. Don't Quit Your Job
If you are currently financially reliant on a day job, don't quit if you haven't already. These next few steps you can do when you're still employed. They can take time, but don't require your day-to-day attention full time. Ideally, you should have 2 years worth of savings, as SaaS businesses take time to ramp up. So start saving while you jump into the next steps.
If you already did quit your job, consider freelancing. This will help connect you with people who might buy your SaaS later, while also keeping you financially stable while your SaaS is getting traction.
2. Build Your Skills
If you don't feel confident in one of these areas, you might not be ready. Just take a weekend here and there and learn the basics. None of this stuff is as complicated as it seems, and you don't need to be an expert right off the bat.
Sales is how you will find and communicate with prospective customers. This doesn't necessarily have to mean meetings and phone calls. Sales can be done through live chats, texts, message boards, and virtually anywhere you can connect with a prospective customer.
Marketing is how you will position and present your solution to prospective customers. You don't have to be a designer or copyrighter, but getting down the basics can help tremendously. You can usually buy assets or outsource, but if you don't know the basics you won't be able to distinguish between good and bad design/copy.
Operations is how you will organize, automate, and scale your idea. Good documentation skills are key here. The better you can document, the easier it will be to outsource, hire, and scale.
This doesn't necessarily mean code. No-code tools can get you to a pretty good minimum viable product in the early stages of your solution. Products also don't always mean dashboards and databases. A website with a form that emails you to do something manually is a perfectly fine way to launch the first version of your solution.
3. Generate Ideas
You may want to go broad and build something that works for everyone, but that is counter productive to building a product that stands out and markets itself. It's better to be the sole expert in a niche than to try to break through thousands of products that all solve the same problem. Try to stick within a niche or industry that you already understand.
You will then want to start with one single problem within that niche. Ideally, one you enjoy solving. For example, don't build a hosting solution that does everything for everyone. Maybe just build a landing page generator for one specific industry or one type of customer.
Most people bomb their first few products. Expect it, and get them out of the way as soon as possible. So don't come to the table with one make-it-or-break-it idea, come with at least 10. Keep the ideas pretty simple, ideally things you can build a prototype of in 4 months or less. Here's a few tips for coming up with SaaS ideas.
4. Do Your Homework
Subscribe to newsletters, podcasts, and blogs (like this one!) related to building SaaS products. Listen to the mistakes of other founders so you can protect yourself from the same mistakes. Many founders don't do this and wind up wasting months or even years of time. Give yourself a head start. By listening to others you can boost yourself closer to their level at a fraction of the time/cost that they incurred learning the lesson for themselves.