Update for my iPhone 4 takes forever. Why?

Ok so I've got an update for my phone it says. When I click to download it, it goes as far as "preparing download" then it like freezes. Won't go any further. Why?

There can be many reasons, if you are trying to update over the air I would recommended trying to update it via computer/usb. The more information we have on our phone the longer an update will take to install, so don't worry if its take a while just let it be, but if your saying that the update won't get pass a certain stage there has to be some sort of an error that is popping up. When and if that happens you should search what the error number/says on google and see what other people have done to resolve the error. But if all else fails just try and restore the phone, hopefully you back it up at some point where you won't loose you stuff!