How to pick up a gerbil
Never pick a gerbil up by its tail. Their tails are not strong enough to support their weight. You may break or dislocate bones in their tail, tear ligaments or tendons, or the skin might deglove which will require amputating the exposed bones.
Gerbils are prey animals, if you come at them from above or behind they will run. When picking up a gerbil approach them from the front. They will be able to see your hand and will probably step right up onto your hand with time.
It may take some time to win your gerbil over. The best way to get a gerbil to walk on to your hand is to bribe them. Sunflower seeds, cheerios, peanuts, and even live mealworms are great treats that gerbils will keep coming back for more. Place your hand on the bottom of the cage with your offering in the pal of your hand. Gerbils are curious and can not resist temptation for long. They will come and check it out.
Be gentle and patient with your gerbils. If you take the process of hand taming them slowly it won't be long until your arm becomes a ladder and they quickly scurry up to your shoulder.