If small children will be using the trampoline, make sure they are supervised at all times and, although children love to jump on it all together, this greatly increases the risk of someone getting hurt. Its best to have just one person on the trampoline at a time.
Trampolines have a lot of metal springs and other parts that would be very painful to land on, make sure these are covered in padding. A safety net surrounding the trampoline is also very important to help stop anyone falling off while jumping. It is also a good idea to place the trampoline on a soft spongy surface such as wood chips and to have the area well lit.
Keep in mind your own fitness level. If you are not normally very active or have some pre-existing injuries etc. be careful when using a trampoline. It is very tempting to want to have a go, but one bad landing could cause some serious injuries, especially to your head and neck.
Yes, trampolines can be a great activity and while you don’t want to stop anyone from having fun in your backyard, as the homeowner, you have the responsibility to keep them safe while on your property.