Get rid of all your gray by applying equal parts permanent ash blond color and 20-volume color developer. Just mix the ingredients up in a color bottle, squirt it on and work it in. Wait 35 to 45 minutes for processing -- gray hair can be stubborn. Shampoo, condition and towel dry. Retouch your roots every four to six weeks. This is permanent; you will have to keep it up or deal with two-toned color until it grows out.
Tone the gray down a bit with semi-permanent ash blond color mixed with 10-volume color developer. Leave it on for 25 minutes and shampoo it away. Semi-permanent color won't remove all the gray, but it will tone it down a bit. This color will also fade gradually over several weeks. To freshen it up, just do the whole thing over. To get rid of it, let it fade away.
Camouflage the gray with ash blond lowlights. Pull strands of your dry hair through a frosting cap, using a frosting needle -- it's kind of like a crochet hook. Pull through a little for a subtle effect; a lot for a dramatic effect. Apply a mixture of color and 20-volume color developer to the hair that you pulled through. Wait 35 to 45 minutes and shampoo it away. Follow up with a good conditioner. Maintain this every few months by doing it all over again. This option is permanent, but it grows out easier than all-over color, since you're not turning all of your hair blond.
If you've never colored your hair, start out with semi-permanent color first. That way you won't have a hard time growing it out if you don't like it.
Color can irritate and stain skin. Always wear gloves when applying color.