If you do, that person could eventually betray you. Even if it is a relative or spouse, don't tell anybody what you are up to.
Bare hands leave fingerprints.
Once your victim places his trash outside his house or office for pickup, it is legal for you to pick it up yourself. You can learn a lot about your mark by sitting through his papers and such. The pros do it all the time. Give the victim time to forget about you and what he's done to wrong you. Getting even too soon makes it easier for him to discover who's doing it.