urm......

most selfish one letter 'I' - avoid it
most satisfactory two letters 'WE' - use it
most poisonous three letters 'EGO' - kill it
most use four letters 'LOVE' - value it
most pleasing five letters 'SMILE' - keep it
fastest spreading six letters 'RUMORS' - ignore it
hardworking seven letters 'SUCCESS' - achieve it
most enviable eight letters 'JEALOUSY' - distance it
most powerful nine letters 'KNOWLEDGE' - acquire it
most divine ten letters 'FRIENDSHIP' - maintain it