A USB drive can contain years of mixed files, but sometimes you only want to send one folder, one project, or a few documents. If the drive is handed over as-is, the other person may browse everything else stored on it.
The safest free method is to copy only the selected files to an empty USB drive. This works well when the delivery is rare and you have a spare drive.
If you reuse the same USB drive, create one folder for the files you intend to send. Check the root of the drive before handoff so old folders are not visible beside it.
Hidden folders and names like "old", "temp", or "backup" do not protect private files. They can still be opened, searched, previewed, copied, or noticed.
GiliSoft USB Encryption is useful when the same USB drive is used again and again. Put the files you want to send in the public area, and keep everything else in the password-protected secure area.