Next time you watch a show or a movie on television, consider what the camera sees. Consider that view your POV (Point of View). There are many different ways to use POV in your story, or maybe I should say, there are different methods of writing and POV is vital to all of them.
Your 'camera' is your eyes, ears and mind. Of course you should also try to work in touch, taste and smell wherever possible. All of your readers are avidly watching your program, plugged into your movie and waiting for your next move.
Like film makers, you will ride around on the shoulder of one or another of your main characters. You can follow very close and know only what your character can know, or you can take a more distant stance and know what most everyone knows. The latter is probably the most common, but really you need to be careful, you don't want to clutter up the page with everyone's thoughts and feelings - a comment or two is more than enough. You want to keep your viewer's attention on your main character(s).
For those of you who go all out with your list of characters (like me), keeping focus centered on your main character is paramount. If you have more than one main character, juggling them all may get a little dicey. I prefer a single main and perhaps a handful of secondarys. Not that I know much about running an office, but it's not unlike an executive with a handful of secretaries. We get to know this secondary group of individuals, but I never really follow any of them. They are merely in the inner orbit around my main. And as we all know, life is cluttered with characters so don't be afraid to do the same in your book.
For those of you who have more than one main character, more than one 'executive', in your story, keeping your viewers up to date on all of them can be quite a juggling act indeed. You never want your reader to forget about any of your mains. One way of doing this is to make a list of the main characters you want to keep track of. For instance, let's say the backdrop of your story is a global war and there is the Middle East faction, the African faction, the European faction and the American faction. Did I miss someone? I didn't mean to, but you get the idea. In each faction you have a main to follow, they may or may not know of each other, but that isn't the issue. What you DON'T want to do is follow one for three chapters, another for two, and another for like six chapters, mention yet another one in one short chapter and then go back to dwell on the previous one. You should try to give equal time to each of your main characters, and enough time for us to get to know them rather well.
I haven't tackled something like this, but I've read several samples. One being 'The Wheel of Time Compendium'. This is an awesome series of books - I believe there are twelve of them now - and it follows a handful of friends through several years as they strive to save the world from the evil lord of the underworld. This series starts out with a group of friends who grew up together, but all too soon these friends go their own way for one reason or another in their effort to accomplish the same goal. Following them is like following the threads of a braid as some go this way and back while others go that way and back. Some interact at one point and others interact at other points.
Robert Jordon did a fantastic job with his characters. They were each full of life and very different from the other. As Robert takes them each on their own journey through the books, you are sorely tempted to stay with only one, but if you did that you would miss out on what the others were doing. Everyone I've talked to about it has told me that they had a favorite character. I think the thing Robert did that made this epic story work so well was he never allowed any of us to forget who any of his characters were. His chapters were enormous and his descriptions were tremendously detailed but his world lived. There were worries and plans and communications, successful or failed, to keep us fully involved with each of his main characters. This is something you need to try to imitate though I wouldn't advise such an epic undertaking the first time around.
If you're going to have more than one main character, you need to keep us up to date with all of them. In Robert Jordon's books he had a healthy dollop of magic and the initial attachment and loyalty of that friendship to build on. Without that, you need to devise some other way to keep us involved, and remember we will be looking for some connection from the very beginning, so don't keep us waiting too long.
Giving each player equal time in your book is vital, also giving us a fully rounded and involving character helps to make them our best friend or worst enemy as the case may be. Like I said before, I wouldn't recommend such a convoluted epic adventure for your first try. But don't wait until you're on your death bed either. I'm sure many of Robert Jordon's readers would like to strangle his ghost for not finishing the story.
POV allows us to get involved. With POV, especially close POV, we can use all five senses to familiarize the reader with your main character. There is rocking emotions, wrenching tears, explosive temper tantrums, or stolid determination. The more you can get your reader to like or hate your character, the less likely they will forget who he or she is later in the book. Myself, I prefer a single main. One character can get into plenty of trouble, juggling half a dozen of them, though a joy to read if well done, makes for a very long book.
So, allow the camera of your pen to see the movie of your story. Hear the cries of anguish, smell the baking bread, taste the blood of the enemy, touch her satiny skin, and watch the moon rise. Let it all be there. It's your point of view. Don't be afraid to share it.