Your printer may add invisible identification data. Laser printers do this by using tiny amount of yellow toner.
If you withdraw cach from ATM, it could be traced back to you. It’s best to take larger banknotes and exchange them for smaller ones by paying somewhere.
You may easily leave fingerprints on tape, envelope or stamps. Also hair, saliva, blood if you cut yourself on paper, etc… There could also be hair in your pocket that could stick to it, if you put it there while transporting it.