I often use just a color adjust at 0.8 or so, but if your sand is very yellow, the darker sand will maybe be too yellow. Or cover the sand by a degree of black (surface shader). And the sand, where the water comes, is usually very smooth, so I would smooth out (or not make) almost all displacement. Perhaps add some warped small ripples.
Then reflection. On higher wet sand usually no-RT, default will do, on very wet sand I set it to RT, but restrict it to above water level (no shiners on sand under water). Distinction between wet and dry sand can be very smooth or very hard, depending on circumstances. When high tide is coming in, distinction is often hard.
And sand grains. Two 0.005 full density fake stones, no color, taken through a transform shader set to world will do nicely.