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Once your hair is shoulder-length, it starts to look weighed down. Opt for a cut that hits between your chin and collarbone — or even shorter, if you prefer! Fake a voluminous look on super-short hair by cutting the sides closer to your head and leaving the top a little longer. Style the top with a volumizing product and a round brush to give it lift. Layers can make your hair look thinner, especially if you opt for a style with a lot of layering. Instead, choose a bob or similar style with a strong, blunt line across the bottom to make your hair look fuller. Avoid blunt cuts that are done with a razor. These can cause your hair to look frizzy and can make it appear even thinner. If you don’t mind coloring your hair, highlights can create a 3D effect, making your hair seem fuller. Lighter highlights should be closer to the top, while lowlights and your natural color should fall towards the bottom.

Summary:
Cut your hair short or medium length for more bounce. Opt for a blunt cut for the most fullness. Get highlights to add dimension.