A routine to avoid running out of storage
Tired of not being able to download new apps because there's not enough space? Unless you have a 128 GB iPad model, I'm sure you have seen the "there is not enough available storage to download these items" or "Storage almost full" awful error. Running out of space is something absolutely normal. Keeping a regular routine to delete the unnecessary stuff on your iPhone shouldn't be a chore, but a healthy habit. And let me tell you a secret: there's no need to delete apps you're not using with these tips.
First of all, the only way to clearly see the items taking up more storage space on your iOS device is in the Settings. You simply need to navigate to General and then Usage to be presented with a loading animation for the system to calculate how the storage on your iPhone or iPad is being used. Don't be tempted to scroll down and give it some seconds to load.
Photos & Camera
I'm using my personal experience for this guide, and in my case the biggest culprit is the Camera Roll. Yes, the photos and video you take will take a lot of the storage. I wouldn't consider myself a serious iPhoneographer but I do take some snaps and videos almost daily. All of those will end up taking up some space, easily reaching the 10GB mark after six months using your iPhone.
And now comes the compromise. If you love showing pictures to friends on your phone, it's going to be hard to let go. I recommend going through the whole Camera Roll regularly and remove duplicates, bad shots and photos you don't need anymore. You can do some pruning directly on the Photos app after tapping the Edit button. That's usually a quick fix that works if you do it regularly. When you're dealing with over 2,000 photos, perhaps it's better to plug your device to a computer and do all the heavy-duty work on a desktop.
Whether you remove the bad pics or want to backup your whole gallery, iTunes should be the most straight forward option. With iOS devices set as storage devices you can copy the pictures from the Finder and Explorer for Windows users. I prefer using a third-party desktop app over iTunes, so I tend to rely an app called PhoneView that gets the job done.
When pruning your Photo library, remember videos take up a lot of storage space. This is not immediately obvious, but some short clips under a minute can weigh 1GB easily. If you have any video over 20 seconds, you should seriously consider removing it from the local drive and, perhaps, keep it available on a private YouTube URL or somewhere online in case you want to show it to friends. There's no other reason for keeping those there with you everywhere you go. This is also applicable for pictures using Dropbox and similar online services.
The last area that normally goes unnoticed are Photo Streams. With this feature enabled, every device using your iCloud account will keep a record of the latest 1,000 shots taken. This is tremendously useful for some, but if you don't really use it and have it enabled, you are going to save 1,000 photos worth of space.
Music and podcasts
If it's not the first item on the list, Music it's definitely going to be the second. The good news is that on that same Settings > General > Usage menu, when you tap on Music you can delete individual albums instead of getting rid of your whole collection. This is probably the easiest and quickest way to free some space on an iPhone — just remember the changes you made if you sync your device with a PC so it doesn't copy all the MP3 files next time you connect to iTunes.
Other apps using audio files such as podcasts player can also bulk up some space. Apps like Instacast or Downcast allow you to delete specific episodes right within the app, so that's the next place to go.
Content catchers: Instapaper and Reeder
For my surprise, the third category of items that make me run out of storage are the read-later app Instapaper and the RSS reader Reeder. If you think about it, these type of apps are designed to provide you with something to read without network access — so all those articles should be stored somewhere, right?
Since the apps themselves are quite light, a good idea (if you don't mind re-downloading all the content) is to delete and reinstall the app. Yes, you might lose some of the settings, but the file size will decrease significantly.
Do you really play Infinity Blade every week? I know I said you wouldn't need to delete apps with this routine, but seriously… When was the last time you loaded up that game? While the typical casual game won't exceed 50MB, definitely not 100MB, anything that tries to replicate a console quality experience will be way bigger than that. Just to give you an example, most Gameloft games will fit into this category. The Dark Knight Rises for instance is 860MB to download and requires over 2GB installed. Fortunately, most games these days come with some sort of Game Center, iCloud or custom way of backing up saved games even if you delete the app from your device.
So what is your approach? Exporting photos older that a year? Keeping an eye on the podcasts automatically download for you to listen offline? Whatever option you choose, just remember there's no need to sacrifice anything you don't want to in order to free some space. Just consider the options available, as an old video you shot or that album of a band you don't like anymore could be the quickest solution.