keep/play (your) cards close to (your) chest

to not tell anyone what you plan to do.

I never know what Martin's next move will be. He plays his cards close to his chest.

• If at first you don't succeed.
• If at first you don't succeed, try, try, and try again.
• if can help it
• If can't stand the heat, get out of the kitchen.
• I feel it in my bones.
• if it ain't broke, don't fix it
• If it ain't broke, don't fix it.
• if it comes to the crunch
• if it weren't for
• if it weren't for someone
• if it weren't for something
• if knows what's good for
• if knows what's good for them
• If looks could kill...
• if memory serves
• If Mohammed will not go to the mountain, the mountain must come to Mohammed.
• if need be
• if push comes to shove
• if someone knows what's good for
• if someone knows what's good for them
• If someone thinks something, they've got another thing coming!
• If someone thinks something, they've got another think coming!
• If someone thinks, they've got another thing coming!
• If someone thinks, they've got another think coming!
• If the cap fits .