What is the best way to remove a splinter from foot of 3 yr old?

See below. Apply ice to the area to freeze it and then see if you can grab it with a tweezers. If not take them to a podiatrist.
Depends. If the splinter is not really causing pain and not deep, i would likley leave it alone and let the skin on top of it peel off and the splinter will come out with out the pain of digging it out. If it is deep in the foot or if it becomes infected you may need to see a doctor.