Shelynn, if after you've bet/bid everyone checks, you've not bet enough. If you've got 2nd pair for instance and you want to see where you are standing (and hopefully take down pot there and then), then betting the pot won't do anything but sweeten the pot for the eventual winner. There are so many variables as Grumbledook says, that I don't think anyone can give a perfect answer. If you think that someone is on a draw and you have the best hand, then you need to bet enough so calling would be a mistake. And just because someone has checked after leading out betting previous round, doesn't mean they have missed flop - on the contrary, if they have been betting out after missing previous flops (to try and take down pot there and then), then a check could signify a "sneak" play.
Generally though Shellyn, if you initiated the betting originally and got one or 2 "reluctant" callers, then a 2nd bet after flop will often take down pot as it will have missed opponents too. Just make sure you don't overdo it, or become too predictable.