This is my take on it. Others may differ.
I'd suggest a CPL first. Landscape & beaches particularly come alive. Enhances blue sky & green foliage and cuts glare and reflections. Mine rarely leaves my 9-18mm on my Oly.

Next, a set of graduated ND filters. While you can bracket, I prefer to take a single exposure - this then gives more freedom to avoid the tripod and still manage bright skies etc

Then maybe a solid ND filter. I started with an ND400 (9 stop) . Between the CPL (about 1 stop down I think) & GND 3 stop, and judicious stopping down the aperture, I haven't found a need yet for anything in between. ....so far