Once you've applied the base coat to all nails, use either a sponge or your finger to smudge on the holographic powder. Work it into the nail without going over the same area too many times. If any areas haven't taken the holographic powder, just dab on more base coat, cure, and reapply carefully. Alternatively, to create an ombré effect on the nail, apply in the same way but add an extra coat of holographic powder to the tips of your fingernails.
Image Source: POPSUGAR Photography / Tori Crowther