Hey there, this is a nice start! I think what could help you the most is having a good balance of hard edges and soft spots. At the moment, I think your overall shape language feels a little soft, so while the details tell me rock, the silhouette of the rock itself seems more like a blob. I think some nice cracks could help too, as I'm not seeing too many of those. I do really like how you have these edges that are pushing with strong highlights, that is really carrying the stylized look for me!
Before worrying about stylization, try sculpting rocks based on real world references. You should always try to understand the source materials basic forms / shape language before trying to bend or break the rules (ie. 'stylize' them).
I use a mix of trim smooth border with a hard box alpha and Orb brushes to sculpt rocks. Some people also like the mallet brushes a lot.
Also this tutorial might be of use. It helped me a lot when I started sculpting rockshttps://www.youtube.com/watch?v=ReYMH6wJ2As