We know for certain there's a new version of iOS coming, and we are reasonably sure there's a new iPhone on the way. Whether you're itching to upgrade to the latest hardware or just preparing to upgrade iOS on your current iPhone or iPad, here's a list of things to do to make sure you don't miss a vital step.
1) Trim the (digital) fat
First off, assess the situation on your iPhone. Is it full? Do you sometimes get notified of an update for an app you forgot you had? Do you buy more iCloud space for backups because of all those photos? Now's a good time to clean out some of those items. Check to see how much space you have by going to Settings > General > About and looking at "Available" partway down the list. That will tell you how much free space you have. You'll need that number later, but for now let's clean out some dusty corners. Start with photos, and delete those you only needed temporarily, or the blurry ones you don't want to keep. Just tap on the photo, then tap on the Trash icon in the lower right corner. Then go through all those folders with apps in them and see if there are any you can live without. Remember you can always install it again later if you change your mind.
2) Get Current
Next, update apps. You know that badge on your App Store icon? It means you have updates outstanding, and iOS 8 has been in beta long enough that a fair number of apps have already been updated for compatibility. When iOS 8 is officially released there will still be an Appalanche, but you might be able to get a little bit ahead by doing as much updating as possible before the iOS 8 stampede to the store.
3) Back That iOS Up
Back Up. Twice. Yes, twice. I know it sounds weird, but "belt AND suspenders" is totally the way to go here. Especially with your precious iPhone data! All those pictures, precisely how you laid out your home screen, all of those little tweaks you made, preserve all of that by backing up to both iCloud and iTunes. First off, it's redundant, which all backups should be, and second, either way you're covered. If you pick up a new iPhone in the store, for example, you can start restoring from the iCloud backup immediately, and if you want to restore from your computer, it doesn't suck that way either.
To back up to iTunes (which will need to be at least version 11.3), plug your iPad in, launch iTunes, and click on your device. Verify under Backup it's set to "This computer", then click the "Back Up Now" button and watch the progress bar until it's finished.
Where to switch backup options in iTunes.
To back up to iCloud, on your iPhone, go to Settings > iCloud > Storage & Backup.
(If necessary, turn on iCloud Backup.) Tap Back Up Now
Where to adjust iCloud Backup preferences on your iPhone.
There's no way to overstate how important this is, if It All Goes Wrong in the course of updating, it's a lot easier to get back where you were when you have multiple backups.
3a) Photo Backup
To save your iPhone photos outside of a backup file, with your iPhone plugged into your computer, go to your Applications folder and launch Image Capture. Your device should show up in the sidebar, allowing you to sync all your images to a selected folder for extra safekeeping.
Image Capture with an iPhone connected to the Mac.
4) Git 'er done
Once you have everything cleaned out, backed up, and backed up some more, now you are ready to make the leap. Take a deep breath, and download the update. You can do this either on your computer using iTunes, or with an over-the-air (OTA) update on your device. When the update is ready, you'll have a badge on your Settings icon. Remember that free space number from before? You'll need it here, to verify you have room for the update to download properly. To start the OTA update, go to Settings > General > Software Update and walk through the steps there to kick off the download and install.
Since I probably have to charge my phone anyway, I usually do it via iTunes which seems to be happier about resuming downloads if something fails partway through (your mileage may vary).
After walking through most of the setup process you can choose to restore from backup, or set up as a new device. It's up to you; Some people start fresh with every major iOS release, some have restored from backup ever since that option was available.
Now that you're all ready for iOS 8, we just have to wait (impatiently) for it to actually be released. I know, it'll be hard for me too. If only there were some way to pass the time till then...