You can't judge a book by its cover.
This is all about first impressions. We need to read a book to know if it's good or bad – we cannot know what it's like just by looking at the front or back cover. This proverb can be applied to everything, not only books.
have an ace up your sleeve : have an effective resource or piece of information kept hidden until it is necessary to use it; have a...
If you wish good advice, consult an old man. Old people have a lot of life experience and wisdom, so it is best to ask for the good...