Generally, frequent handling will keep your gerbil quite tame. If your gerbil is difficult to handle, and all else fails, bribery with their favourite food, for example sunflower seeds, can help make a gerbil more amenable to handling. Gerbils are particularly difficult to catch if they escape from their cage, so bribery with their favourite food will definitely help in this situation!
Here are some handy hints on picking up gerbils…
Never pick up a gerbil by the tail – they are delicate and can easily break.
The best way to carry a gerbil is to simply cup them in the palm of your hand. It is also possible to gently hold them by the scruff of the neck (the loose skin on the back of the neck) to prevent the gerbil from getting away, if necessary.
If absolutely necessary you can hold a gerbil firmly by first holding them by the scruff of the neck, and then holding the base of the tail with the other hand (cradling the gerbil’s back in the palm of the hand holding the neck). You must only hold the very base of the tail as close to the body as possible, and not too tightly.
If you are not comfortable picking up an untamed gerbil as above, then allow the gerbil to walk into a cup or can turned on its side, and then tip the cup up to carry the gerbil. Place a hand over the cup as gerbils can jump surprisingly well. You can also use a cardboard tube, e.g. from a paper towel roll, for this purpose.