Hello SM,
My method is to paint 'ballast effect' where I plan to lay the track. My whole baseboard is covered in 3mm cork and this gives a 'texture effect' to the paint. I use ordinary artist's acrylic paint (cheap from the Works) starting with ultramarine blue mixed with burnt sienna brown to block in. When dry, I use a dry brush technique and / or very porous sponge to dab on the lighter colours ( shades of biege and - here in Essex - a surprisingly pinky grey). And finally mossy green.
If you want hyper-realism, this won't do, but if you're happy with a reasonable effect, it's a good solution.
I've recently changed nearly all of my track and haven't tided up the painted edges yet, so the 'ballast effect' isn't as parallel to the track as it should be in this picture. But hopefully, you can see whether the effect is close enough for your needs.
Enjoy.