Below is a chart of all twelve (12) key signatures, and their enharmonics, with proper placement of sharps (#) and flats (b) in each clef. Each Key Signature represents both a Major Key and a Minor Key. The Minor Key is called the "Relative Minor" as it is always a minor 3rd down (three half steps down) from the Major Key.
In the chart below, the Major Key is shown above the Treble Clef. The Minor Key is shown above the Tenor Clef. The top group shows all the flat keys. The bottom group shows all the sharp keys. Again, middle "C" is represented for each clef. Both groups begin in the key of "C", no sharps, no flats.