Owning a Vespa in the USA means you'll probably want to put your scooter in a truck at least once or twice.
Find a flat level surface to load on. There's nothing worse than trying to load a scooter in a steep driveway.
Use a ramp. Ramps are great because they don't require any heavy lifting and you can load the scooter by yourself. I'd suggest getting a motorcycle or scooter loading aluminum ramp. Spending some bucks on a good ramp will make your loading easy and safe every time. For those of us who don't have lots of cash to spend, a nice, straight 2x12 will perform the same function for less money.
Drop the tailgate of the truck and line up the bike behind it. If you have a friend to help, have them stand in the bed of the truck. Take the scooter off the stand and roll the scooter up the ramp with your friend helping as it goes into the truck.
If you do not have a ramp put the scooter behind the open tailgate and lift the front wheel onto the tailgate by grasping the front suspension. The second person should be in the truck helping to hold the scooter steady by the headset. Once the front wheel is in the truck (back wheel still on the ground) move around to the back of the scooter. Bend your knees and get as low as possible grabbing hold of the rear frame. Lift with your legs, slowly walking forward while your friend steers the scooter into the truck.
Now that you have the scooter in the truck, place the thick block of wood in the middle of the bed, nearest the front. Roll the scooter forward so that the front wheel rests against the wood. This block of wood protects the front fender from damaged against the front bed of the truck.
Using the tie downs hook one into each front tie down point on your truck. Make sure the tie down points are at the front of the truck bed. Just leave them loosely in place while you make sure the scooter is off the stand and centered. The concept is to totally compress the front suspension against the block of wood, creating a forward and downward force, which will hold the bike in place. Hook the ends of the tie downs onto the mirror mounts (this only works for Vespa's made after 1968) and tighten the tie downs until they are really tight. One trick on older scooters and on the new autos is to buy a transporter sock. The transporter sock effortlessly goes around your handgrips and headset ensuring a safe hold for your scooter. Using this method it is not necessary to put the bike on its center stand.
It is not necessary to secure the rear of the bike but you can if you want to. All it needs is to be secured so it can't move from left to right pivoting on the forks. You could simply attach a rope to the rear tie down point, loop it around the seat lock bolt or rear rack and then secure it to the second rear tie down point. These instructions can be applied to a van if you have a place to secure the front wheel.