Deboss the sand
Choose a simple fonts such as tekton bold, set you message.
Add a bevel and emboss layer effect. Chaneg the shadow blend mode to color burn, and the highlight mode to soft light.
Change the fill opactiy to 0% leaving the effect opacity at 100%.
(these next 2 steps are optional for an even more convincing look if you have the time, and are looking for a quality high res image) Displace the sand
Save a flattened .psd file of just the bevel layer on a white background. Run a filter >>distort>> displace and use the .spd file you made.
Raise the sand higher on the outer edges
Make a layer over the entire image of a repeating pattern of the sand all disturbed.
Add a layer mask that hides all.
Paint on the layer mask over the edges of the type with a rough brush to reveal the higher up sand layer on the outer edges of the type.