Textures, shading, and normal maps can help a lot with the effect. However I have a different tip that can help, especially (but not exclusively) if you happen to use the subdivision surface modifier as part of your workflow. This works as a complement to using the sculpt tool, or just moving vertices around manually.
(Sorry if this isn't what you're looking for or it's too detailed - but maybe it can help somebody else who happens to find this post!)
Before you've applied the subdivision modifier, you can select specific edges and mark them as edge creases.
Here is a weird little character thing for demonstration:
And here is a preview of what it would look like (so far) when the subdivision modifier is applied. It's too soft and rounded:
Select the edges you want to be creased:
Press ctrl + E to open the edge menu and choose "edge crease" (or press shift + E to use edge crease immediately):
Then drag your cursor back and forth to play around, or use the window that appears in the bottom left corner to configure how extreme you want to get:
Here's the extra pointy boi:
As long as those edges are still marked when you hit "apply" on the modifier, they will stay in the final result! (You'll see I added another sharp crease here)
Even if you don't have any modifiers, if your edges are still marked as creased, and you enter sculpting mode, they stay pretty crispy: