Disney has it's own security and while crime is not unheard of , it is thankfully not a major problem. Off site is a slightly different matter but still , IMHO , you are more at risk wandering around a large city in th eUK than you are in the tourist spots in Orlando.
That said there are the usual warnings that need to be heeded. Criminals do know that tourists generally carry more available cash and valuables than "locals" so anything that doesn't advertise this fact is a good idea.
When Driving Around
If you have baggage/shopping in your car, put it in the trunk where it can't be seen
Don't leave maps in plain view
Try to know your route before setting off ( trying to read a map when driving is a sure sign of a holiday maker)
Don't leave cameras etc in a position they can be seen
Park in places that have good lighting and preferably near to public/busy places
When in your room/villa
Don't leave the room/front door open ( You'd be suprised how many do this !!) when you're running to and from the pool
Don't open the door unless the person knocking is known to you, expected or can identify themself. If in any doubt about their claims/ID call the front desk to ask if they are who they say they are. There were cases of people claiming to be security knocking on doors, then robbing people
If you have a room safe, use it. ( if not put passport TC and valuables you don't need in the safety deposit boxes at the front desk
As is said, generally Orlando is a pretty safe destination, but that doesn't mean it's crime free. You can reduce your risk by using common sense and simple things that seem obvious IF YOU THINK ABOUT THEM. Even in the parks I'm amazed by the number of people that leave cameras, shopping and purses on the back of strollers when they go to a ride. It is rare for those valuables to go missing, but it does happen.