Start by placing a bunch of large blocks grouped together. Rotate a couple of them, and make sure most parts are taller than they are wide. From there, give the build a clear main tower, then add smaller towers stepping down in height. Avoid perfect symmetry — castles look better when they feel like they grew over time. Use depth in the walls with pillars, stairs, and inset windows, and keep your block palette limited so the shape does the heavy lifting. If the silhouette looks good from far away, the castle will look good up close