Hints for Spelling Major and Minor Seconds

  
     Look at a piano keyboard. If you remain on the white keys (no accidentals) there are only 2 pairs of notes with no black key in between them, b-c, and e-f. These are minor seconds, and all the others are major seconds.
     Sharps move a note up, flats move it down. Always think in terms of moving towards or away from the other note. Moving the upper note up makes a larger interval, while moving the lower note up makes a smaller interval. Moving both notes in the same direction doesn't change the interval.
      If you know your key signatures, any time the upper note is in the key of the lower note it is a major second. (i.e. C-D: There are no sharps or flats in the key of C major, so D is in the key of C major, so C-D is a major second.)