When you start a new chapter or section, if a significant amount of time has passed, be sure to tell the reader so s/he doesn’t think something was missed or lost. These breaks are intuitive indicators that something has shifted, unless it’s one of those chapters that ends with a cliff hanger. Assuming that’s not the case, if the change is dramatic, such as years have gone by or the viewpoint has shifted to another character, clue in your reader as quickly as possible. Remember that losing your readers doesn’t build suspense, only annoys them.