Start by washing and shampooing your hair as usual. Rinse out and squeeze our as much water as you can. While your hair is still moist, apply your gray hair shampoo.
Do not be too stingy, take a big lump and distribute throughout your hair. You should not massage it into the scalp but carefully distribute it it along the hairs.
How long a gray hair shampoo should be left in may differ between different manufacturers. So read the instructions! It's important not to leave it for too long, it might give a purple tone.
Rinse thoroughly the shampoo and then finish with a conditioning treatment. Gray hair shampos are dehydrating.
Repeat this procedure 1-2 times a week.