The Brown Scapular is properly worn as a symbol of devotion to Mary and of Carmelite spirituality.
I have been wearing one for about a year. I have also been formally invested in it, twice (the second time was just because I was not sure if it had been properly done the first time and it does not hurt to have it done again). I do take it off to shower, swim, or when it needs to be laundered. If I have a substitute one handy I will put that one on while my primary one is in the laundry.
The Brown Scapular is not some lucky charm for protection. Mary protects her devoted children whether they happen to be wearing a Scapular or not.
The official Scapular catechesis is here if anyone would like to know more about this devotion.