Any advise on how to handle players that don’t play their character’s alignment?

Dear @ChrisPerkinsDnD, any advise on how to handle players that don't play their character's alignment? (ex: good gnomes doing evil things)

— Leonardo Raele (@LeonardoRaele) April 29, 2016

Say: "That action is not consistent with your character's alignment."

You can also declare that evil PCs earn 0 XP. https://t.co/M6wKKPYdiU

— Christopher Perkins (@ChrisPerkinsDnD) April 29, 2016