I am stealing the idea for this post from Tara Maya, who posted about the difficulties writers can have showing the passage of time in novels. Specifically, what to do when skipping ahead in the story. It doesn't really matter, in my experience, if you're talking about jumping an hour, a day, three years or three centuries. You need to keep the narrative flowing through these 'passages of time' (to coin a vile phrase).
What I think is important when skipping ahead is to keep the focus on the story, so that you are talking about the same thing (whether plot, theme, character, setting, mood or whatever) while you make the transition. Pick a story element and use it as your transitional device. Is a character waiting for news? Talk about the waiting while the time passes ("It took me three months to hear back from Derrick; I got his letter on the twentieth day of December"). Huge spans of time? Focus on something big that lasts through the eons ("As the years passed, the great Thorndyke mansion fell gradually into decay" or "Kingdoms rose and fell on the plains of Araxxara, and the great mountain outlived them all, standing imposing and some other adjective..."). You can also, for long leaps across the years, talk about an object ("The Vermeer Stradivarius passed through many hands before it found its way into those of Jakob Meerver...").
The point is to keep the narrative unbroken. What you don't want to do is have the story come to a stop at the end of one time period and then attempt to restart at the beginning of the next time period. The story must keep going during/across the time passage.
An exception to that rule is of course the chapter break, but only if your book is structured so that chapters generally begin further in the future than the last one ends. The reader will catch on to this structure quickly enough so you don't have to do much work aside from remaining consistent. I just read a lovely book where chapters alternate past/present consistently, and I wasn't confused ever. In my last novel, I think I was a bit clumsier handling passage of time than I could've been. My next novel will deal with it better, I swear.
I also think that this technique, of remaining focused on a story element through time changes, works with going backwards in time as well, for flashbacks (ugh) and whatnot. As long as the reader still knows what you're talking about, still is aware of the point of your narration, he will follow you along a great many tangents and timelines. But you have to give them something to hang onto while you gallivant across the years. So connect your timeline together with devices that form the backbone of the story. Don't think of your movement out of the story's "present" as breaks, but as digressions that are part of a larger framework, and tie them to your narrative present somehow.
The other thing to remember is that, very likely, any of the narrative/structural problems you'll come across have already been solved in any number of ways by good writers. I highly encourage you to look at books you admire and see how other writers have solved these problems in their own novels. Remember always to read like a writer, to learn from those who've come before us, and that there is no shame in standing on the shoulders of giants when we ourselves wish to rise above the crowd. That's a lame image but I'm tired, okay?
Caveat Lector: This all supposes that you write the sort of story that I write, in which a flowing and unbroken-seeming narrative is important. If your intent is to sometimes disorient the reader, or if you are trying to make the skips in the timeline stand out, you should ignore all of my advice. There are lots of types of stories, and lots of ways to tell those stories.