Delta's right in most of what he says above. Your car has a maximum towing capacity, it's pretty easy to find in the handbook, or just Google your car for technical specifications. That limit is the combined weight of the trailer and the load.
Car transporter trailers also have load weight limits, so it's important to get the right trailer. They can be rented quite reasonably, IIRC the guy local to me charges £35/day, and you'll need to buy a number plate for the trailer.
So you need to know the kerb weight of the car to be towed, select the correct trailer, know it's weight and have a car capable of towing the combined weight......
@Tigz, I'm afraid that legally, your Galaxy can't tow a Safrane on a trailer