As Egon pointed out, once the community cards are dealt, often there is a possible straight. The times when I pay the most attention to it are when high cards are involved, ex. a board of A-Q-7-4-T, where KJ made a straight. Any time a hand with 2 high cards will make a straight be careful, that includes hands like QT or even J9, since people play these hands quite often. The betting pattern is, of course, what will help you determine if he does hold that hand, but you can only realize it if you pay attention to the board. Also, frequently players will raise your flop bet when they hit an open ended straight draw, ex. they have KQ on a J-7-T board, which is often a great play since they can, with that raise, either take the pot down right away, get a free card or at least create deception.
As far as predicting a straight with low community cards, pay most attention to 2 gap boards, such as T-9-6-A-2, because many players love playing connectors, particularly suited such as 8-7s which, on that board, makes a straight. Low cards with 2 gap always hide that possibility.
As, again, Egon pointed out, no matter how careful you are you won't be right all the time, especially considering that some players do a really good job in decieving. But studying the board and betting patterns will allow you to save yourself sometimes.