That means not owning a cell phone. Maybe not using a phone at all. Even possessing a land line or using pay phones might not work.
You also need to use cash. But possibly only make withdrawals directly from a human bank teller, and not an ATM. You'll still show up on bank cameras though. Maybe check cashing and pawn shops is the way to go. Just having a bank account could be problematic, because oft he transaction register.
Using paper cash, you'll still have to consider serial numbers on bills as clues in the long run. Like it or not, the paths of exchange that bills follow can be traced to a degree, using the same imaging software that post offices use on mail, and banks use on paper checks. It's not as reliable for the smaller bills, but for larger denominations, they tend to take short paths exiting the bank (mostly via ATM) and then immediately returning to the bank through business deposits.
So even if you float through space, absorbing all light like a black hole, your gravity will still influence the light-emitting bodies around you.