Have realistic expectations. Don't expect a tired child to be well-behaved. Still developing physically, she is going to drop, spill, and fall down sometimes. So don't give her milk in grandmother's antique tea cup. Understand your child's needs.
Many behavior problems occur if a child needs food, rest, or attention.
If your child misbehaves look for these causes first. Preschoolers want to please adults, especially parents, so they respond to praise. The more you praise a behavior, the more you'll see it. Maybe Bob could play with the truck now, and Tammy you could play with the blocks. Then pretty soon you can switch.