Place two "No Parking" signs on either side of your driveway. Attach the signs to the top of the wooden stakes and insert the stakes in the ground. Drivers must be able to read your signs easily or you cannot expect their behavior to change. "No Parking" signs are available at any hardware store.
Run a yellow nylon rope across the opening of your driveway. Hammer one nail into your mailbox and another into a tree on the other side of the driveway. Tie a small loop on either end of the nylon rope so it hangs taunt between the two nails. Hook the first loop on the nail on your mailbox and the other end to the nail in the tree. Use nylon rope to minimize fraying during the winter and rainstorms.
Erect a short picket fence with an opening gate at the entry of your driveway. Choose one with two hinges or a sliding center that lets you open the gate from inside your driveway and from the access street. A remote control option is convenient but also costs more to install.