I have just started working on a novel. The idea(s) is/are original to me as far as I know. But what if I inadvertently use someone's idea? I guess it is OK to generally use a plot, they are pretty much recycled anyway. But what if I accidentally use someone's theme or main ideas? I suppose I won't get published if the other writer beats me to the punch or is well known. But is there some sort of due diligence I should engage in before I begin?