I have a brain for sequential fiction. It's my curse. I write a story, and then I see exactly where those characters are going next the minute I write the end. Now, not everyone thinks this way. There's nothing wrong with that. I like a good stand-alone novel. But...I also adore a well written series. It's limits the number of authors I'm exposed to though, I admit it. A series is an investment, you don't want to get three books in and discover the author isn't what you expected.
Or worse, that the a subplot you were invested in doesn't pan out in any way. Or that the ending is awful. It can be utterly disappointing to see a lackluster ending to a series you love.
So as a writer and a reader, I never want my own readers to go through that. I want them to be satisfied at the end of the arc.
You've most likely seen this diagram before.
This is generally referred to as "Freytag's Pyramid" and is the most commonly accepted diagram for a story arc. Any kind of story. Short stories, novellas, novels, etc. Now, with a stand alone novel, this diagram (along with it's variations and genre specific versions) is usually all you need to plot with.
You should also note that the arc is taller than the pyramids. See, only a little bit of information to tease the overall arc should be included in book one. It's a subplot, not the main plot. You need to be focused on the main plot while carefully asking questions that lead into your main arc. Book two will require more of the subplot. You need to make sure that the latter half of this book involves the series arc in a more meaningful way so that it all ties into the final book. The final book won't be be a plot within the series arc, it's going to be the series arc. Sort of in miniature. It'll recall things from each proceeding novel and then pull you into that plot you've been teasing of the past books and bring it to conclusion.
I generally know the finale of the series by the time I've finished the first draft of the first book. It's important to at least have an idea of where you're going. Sure, you can (and there are many an author that has) jump from stand-alone to series after publication.
But if your already thinking about what's going to happen in books two, three and four while writing book one? You might be a sequential author. That's when things like Series Bibles come in handy. There's a lot of organizing, plotting, planning, and timelining that goes into writing a series. It's always better to do that work at the front end, rather than have to go back in later and do it after you've written three novels with no end in sight.
It might seem like a lot of work, but it's definitely worth it. Obviously, there's no iron clad "right way" but I can tell you that this preliminary work makes my life a lot easier.