Some people have added pads under the tank. Some don't. What you need to watch out for is to make sure the tank is level, even over time. If it isn't level undue stress can be placed on the tank seams and you risk a rupture. I don't have anything under my tank, on hardwood floors, b/c I worry that overtime it would becomes un-level.
Some people add covers over their tanks, hoods, or screens. All of these help to prevent fish from jumping out. Depending on your tank, adding a screen over the top of it can work better then a hood. Now some fish are more prone to jumping out then others are, so it is good to research your fish before you purchase them to make sure you get proper fish for the size and type of tank you have.