Tarantulas (depending on the specie) can be handled on an occasional basis for them to get used to being handled. Regular handling is strongly discouraged as this can stress out your tarantula.
If you must handle your tarantula be gentle. Terrestrial or ground tarantulas should be handled close to the floor to avoid serious injuries in case your tarantula jumps or falls. When you are handling your tarantula, be sure you are handling it where it can’t run or hide in case it escapes. Be sure to always test your tarantula’s temperament before handling it. It is also important not to breath/blow air on your tarantula as this can spook them and cause them to jump/run.
The best way to handle your tarantula (after temperament testing) would be to place your hand flat on the substrate and gently prod your tarantula on its hind legs or abdomen and let it walk to your hand. You can also let your tarantula climb over the tank and let it walk on your hand.
Another way to handle your tarantula is by using a smaller deli cup and placing it on the substrate and let your tarantula walk into the cup by touching your tarantula’s hind legs or abdomen with either by paintbrush (or pen) or your hand. This method can also be used for aggressive species.
The last method is called the pinch-grab method. This is done by placing your thumb and your index finger between the tarantula’s 2nd and 3rd legs while applying a little pressure and picking the tarantula up. This method is highly discouraged.
There is also another and safer way of doing picking up your tarantula. While using your thumb and middle finger to grip the tarantula between its 2nd and 3rd legs, you can also place your index finger on top of the chelicerae to secure the fangs. . This method should only be used if you are going to treat your tarantulas for injuries/dehydration.