Safety is your responsibility. This article is not a substitute for qualified in-person training.
If you are online, you can watch the video.
3 TO 1 HAUL
Make an overhand on a bight on the brake strand of the GRIGRI to be hands-free.

Make a friction hitch (e.g. autoblock) on the load strand of the GRIGRI. Test it.
Redirect the brake strand through the carabiner on the friction hitch.

Keeping a hand on the brake strand, untie the overhand on a bight on the brake strand.
You now have a 3 to 1 hauling system.
Get in a good position and haul. For every 3 feet of rope you pull, the climber goes up 1 foot.

When the friction hitch gets too close to the GRIGRI or the ergonomics are not practical anymore, push the friction hitch far towards the load.

Then start hauling again.
6 TO 1 HAUL
Tie another friction hitch (e.g. Klemheist on a Dyneema runner) to the last strand of your 3 to 1.

If you are tethered by the rope clove hitched to the anchor, take the back strand of your tether and pass it through the carabiner on the friction hitch you just made.
You now have a 6 to 1 hauling system.
Get in a good position and haul. For every 6 feet of rope you pull, the climber goes up 1 foot.

When a friction hitch gets too close to the GRIGRI or the clove hitch of your tether, or the ergonomics are not practical anymore, push the friction hitches far towards the load.
Then start hauling again.