The most selfish one letter word

   I                           (AVOID IT)

The most satisfying two letter word

   WE                               (USE IT)

The most poisonous three letter word

   EGO                        (KILL IT)

The most used four letter word

  LOVE                  (VALUE IT)

The most pleasing five letter word

  SMILE                     (KEEP IT)

The fastest spreading six letter word

  RUMOUR               (IGNORE IT)

The hardest working seven letter word

  SUCCESS                    (ACHIEVE IT)

The easiest eight letter word

  JEALOUSY         (DISTANCE IT)

The most powerful nine letter word

  knowledge             (ACQUIRE IT)