What signals on the face/body do you have your MIFs give to the pitcher to let them know how many looks and when they are going to pickoff?
Doesn't matter, they'll still screw it up.
The simpler the better. I would have a sign for either 1 look or 2 looks, that's really all you need. You can have a no look or 3 looks, but I'm not sure it makes a bigger impact.
Hand on jersey = 1 look, hand on belt = 2 looks. Glove open = 1 look, glove closed = 2 looks. Touch cap = 1 look, no touch of cap = 2 looks.
Best idea is to talk to your kids and see what they're most comfortable with as it's they're communication system. Just remember the more options you give them the bigger the opportunity for miscommunication.
Had a coach one time that had the SS call out a number. If it was even it meant throw after 3 seconds...I think. He also had rules for odds, numbers that ended in 3...etc...kind of complicated but effective.