To naturally blend away your gray, use the shade closest to your own.
To turn gray into highlights, choose a color that's one shade lighter than yours.
If your desired color is between 2 shades, try the lighter shade first. You can always go darker next time.
Start timing yourself after the application is completed. And don't guess . . . use a timer or a watch.
Apply only to DRY hair.
Take only 2 minutes to apply.
Apply to gray at temples or to patches of gray first . . . to assure better coverage in these color-resistant areas.