To secure it I use Kinesiology tape.
I put two strips in a cross over the sensor.
The first strip, I leave the plastic backing on the middle bit where it covers the sensor so it doesn't stick to the sensor and can be easily removed.
I did try once without any tape but I felt so nervous about snagging it that I soon put the tape on.
Having said that, many people don't use tape or anything.
It is worth checking mid way through the life of the sensor.
The one I have on now was spot on the first day, but after a week had drifted low by about 1 mmol/L then came back up to about 0.5 mmol/L.
The message is that the Libre is wonderful for showing trends over 24 hours but isn't as reliable as a finger prick to show your current BG.