I am all about planning! This is what I do for almost all of my stories and it's what personally works for me.
1. Have an idea.
I keep an entire notebook full of every idea I get. Even the ones that are tiny and could never function on their own. If you get enough of them, eventually they will fall together!
2. Get to know your characters
Ask yourself stupid questions about them. What's their favorite color and why? How would they react to different situations? How do they speak? Treat them like they're a real person. Every question you ask yourself is building them up from a super sturdy foundation. Dialogue and everything else will be much easier afterward!
I make about three outlines for each story I write (well, the ones over 3,000 words, at least). The first outline is to map out how I want the story to go. I plot the beginning, middle, and end very basically. The second outline goes a little more in-depth. I thicken up the plot and add side plots, additional characters, and world-build a bit. Then the third outline is always my favorite. I go super in-depth. I plot out how I want each and every chapter to go in extreme detail, plan conversations that will happen in said chapters, and plan character arcs. By the time I actually begin writing, everything is much easier and flows really well.
4. Keep inspiration close by
I can't tell you how many pictures I have saved on my computer that help me get over writer's block fast. Having the things that inspired you to write your story close by help more than you can possibly imagine.
I know this won't work for everyone but I thought I'd share it anyway! :D