Signs... they're all around us all the time, God sends them to us to help us through this world. They're everywhere in our lives. A sign can be words from people around us who know nothing about that sign they're sending. It can be a dream that you dream just once, or one that keeps repeating everyday until you understand. It could be something that you remember out of the blue, or a song you barely hear that is played on the radio, a movie you decide to watch just to find out that it matches something in your life. It could be just a feeling. It could be seeing yourself in the future doing something, not a premonition of course, but the way you keep thinking of yourself doing a certain thing in the future for no known reason.
They're everywhere, and it's up to us to either pay attention to them or ignore them. And if we decide to accept God's help, then there's the problem of how we interpret the signs, and the other problem of trying to understand what is a sign and what is not. We usually choose the things we wish to be signs and say they are, then we interpret them the way we want to. Then when the opposite happens, we say but we followed the signs. Truth is, our minds might be the only place where these signs exist, where they were created, where they were interpreted, where they were used, and then when things don't work out the way "our" minds told us they will, we blame the signs and forget to blame the mind that made them up.
Bottom line, if we decide to believe in signs, then we'd better be really wise about them. It's better to think of a sign as a way God tries to comfort you, reassures you, or cheers you up. It's better to have your life not depend on these signs. If I have learned anything from believing in signs, it's that it's really easy to make up your own signs, and it's even easier to misinterpret them. So be careful with them, and never ever act/react according to a sign, but instead think of it as a way that God sends you his support.