I start mobile first and only use min-width
I've found it a lot easier that way
by defining a min and a max on a media query, there is no cascading effect whatsoever, any selectors defined in that query will only effect that query.
for arguements sake, say you had a div on mobile first it was 100% width
then for your min-width:xxx max-width:xxx query it was 50%
beyond your max width you want it to be 50% still, however it will go back to the 100%, unless it's specified again,
however with only a min width it will stay at the 50%
if that makes any sense