Can I say 'careful for'?
Careful for is usually only used to express an amount of time that someone needs to be careful. e.g. "You should be careful for the next few weeks whilst you recover."
Careful is more commonly followed by 'with', 'when', 'of', 'about', or 'in'.
Examples of careful in a sentence
It couldn’t hurt to be careful.- Seeing Stars by Diane Hammond
Quinn was extra careful, wiping the sides of the tubs in case one of them had dripped.- Seeing Stars by Diane Hammond
Be careful with the sugar—it goes from amber to brown very quickly.- Mark Bittman's Kitchen Express: 404 Inspired Seasonal Dishes You Can Make in 20 Minutes Or Less by Mark Bittman
He had been careful in his report to Group HQ of his lone flight to Le Havre.- Charlotte Gray by Sebastian Faulks