You'll need your treats as usual.
Also get your dog and a toy of theirs. A toy is the easiest thing to teach GRAB with, but once you have the method you can transfer it to other objects.
Get the dog to approach the item. If they stiff it, give a treat.
If they lick it, give a treat.
If they full on grab it, give a treat. The idea is to gradually increase the requirement to get the treat. When they grab fully, I give a jackpot, or a small hand full of treats.
Next is to transfer the item out of your hand. Now you get to use your hand signal ( I use a claw motion) and your verbal, GRAB. The idea is to only give a treat for a full pick up and hold.
Here is the full motion.
This is a look at the steps with something my dog has never grabbed before. These are the steps you look for to increase the requirement.
Here's the full thing!
You can have your dog pick up near anything!
I have it to where my dog will pick up my pen if I drop t, even without a command.
GRAB is a great tool for many other commands! Check back soon for more training!