Remove the doors from the cabinet fronts. Remove the drawers. Take the hardware off the doors and drawers. The hardware includes the hinges and handles or drawer pulls.
Clean all surfaces. Debris, grease and other contaminates can prevent you from achieving a professional finish. You will end up with blotches where the stain did not adhere to greasy patches, or speckles where dirt is trapped under the stain. Thoroughly dry cabinetry overnight.
Sand the stained surface to remove the glossy finish and roughen the surface. The gel stain will not stick to a glossy, smooth surface. Wash the surface again to clean up the dust from the sanding. Dry thoroughly.
Use the brush to apply the gel stain. Brush on the stain in a thin coat, going with the grain. Add only a little stain to the brush and apply in short, quick strokes. Work in a small area at a time. Work from one finished area to the next area rather than skipping around. This will help you apply a thin coat and avoid uneven coloring. Let it dry overnight. If the finish is not dark enough, apply another thin coat and let it dry again.
Apply a clear wood finish to seal in the stain. You can apply the finish with a clean rag. Apply the finish lightly. Let the finish dry and repeat.
Reassemble the hardware onto the cabinets.