Hard Riddles: #Stumped Volume 6 for Teens, Adults, and Genius Kids

I'm two four-letter words;
when you change one letter
I go from caution to something used,
I give you a heads-up,
or can be quite tattered,
like a pair of discarded shoes,
What two words sound the same
but are different
as described by these clues?

NOT YOUR TYPICAL RIDDLES: Mostly all are creatively written in a longer RHYMING FORMAT (What Am I, or Guess The Word)AND You won't find any old, rehashed riddles in this book - All of the riddles are Original.