The Lord made that clear when He said in Matthew 7:5 "Thou hypocrite, first cast out the beam out of thine own eye; and then shalt thou see clearly to cast out the mote out of thy brother's eye".
When next you feel the need to criticise anyone or anything be sure to do these.
Take a rain check. You should know the true feeling behind your criticism which shouldn’t be base on jealousy because a little bit of it could make you sound sour.
Don’t jump: Some people could criticise what they know absolutely nothing about. So, make sure you have a good knowledge of what you’re talking about else you just might end up looking foolish.
Consider what to create: Consider what you intend to achieve with your criticism, which will determine the form your words will take. I might not be right but I think criticism tends to gear towards destroying than constructing. I hope you do understand; there's a possibility when you're trying to run someone down you might get run over. Spend no time tending to others business unless it is to make it better. Remember, when you’ve got a beam in your eyes, there’s no way you can take the moth out of someone else’s.
Find a base: You must not always have an opinion about everything and everyone. If you feel the need to, you should ask yourself on what basis? As a friend, family member, acquaintance, well wisher etc.
Be human: Even if you have a clear knowledge and the right to criticise a person or thing, let humanity take precedence. Your words shouldn’t cause harm that can’t be handled. However, tough people will still know how to ride through such rough roads created by your words.