Determine in advance the approximate size of the object before purchasing the tarpaulin.
Place the tarp over the object. Make sure the object is covered by the tarp as much as possible. Then you can choose to use tension rubbers where needed. Tension rubbers can be easily attached to keep the tarpaulin in place.
After the job is done, it is best to fold the tarpaulin back up clean and dry and keep it out of reach of UV rays. This way you will keep the tarpaulin in the best condition.