If you’re excited about the forthcoming iPhone OS 4.0 update, you’re not alone. Here’s how you can have a smooth upgrade by getting ready for the latest and greatest ahead of time.

iPhone updates are always a big deal, particularly major ones such as the forthcoming iPhone OS 4.0 announced in early April. Third-party developers have been working feverishly behind the scenes to make sure their hard work is compatible with Apple’s latest, but that doesn’t mean you can’t also do a little preparation in anticipation of its release, expected sometime this month.

As always, your pals at MacLife.com are here to help guide the way -- so read on and let’s get ready to rumble, iPhone OS 4.0 style!

Clean Up Your iTunes Apps

If you’ve used your iDevice for a while now, you’ve probably accumulated a lot of apps -- for example, our personal copy of iTunes is home to nearly 700 of them, including universal apps which run on both the iPhone/iPod touch and iPad. Now would be a good time to take inventory and maybe even do a little housekeeping.

With each new iPhone OS, there are some unfortunate apps that become orphaned and may even cease to work at all with the latest version. One such example is Veiosoft’s DataCase, one of the earliest and best apps for transferring files to your iDevice, which has been seemingly abandoned by the developer after the most recent 1.1.1 update back in September, 2008. That means it’s never quite worked right on OS 3.x, and users who paid out their $6.99 are left to search for competing utilities that are updated more frequently. (DataCase is still for sale as of this writing, but based on a wave of negative reviews since the last update almost two years ago, it’s clearly not recommended for newer firmware.)

Granted, DataCase is less than 1MB in size so it’s not a big hardship to just leave it on your hard drive, but removing it and other unused, unloved or simply outdated apps from your iTunes can only help keep the software running lean and mean. After all, who wants to wade through hundreds of unused apps in search of the one you really want anyway? Click on the Apps icon in your iTunes sidebar, select the app you wish to remove while holding down the Control key and select “Delete” from the submenu.

Of course, deleting an app from iTunes doesn’t mean you’ll have to buy it all over again should the developer come calling later with an updated version. iTunes remembers all of your purchases -- regardless of whether they reside in iTunes at the moment or not -- so you will always be able to download them again for free, unless the developer specifically releases a separate new version for a fee, as was the case with the popular Tweetie 2 app (which has since become the official, and free, Twitter app).

We’d advise that you back up your unwanted apps before emptying your trash -- you never know when you might change your mind and decide to reinstall something, especially if it’s an app that vanishes from the App Store due to some change in Apple’s policy, similar to what happened with the Google Voice apps in the past. (Although keep in mind, Apple can always remotely “kill” apps they don’t want you to use, but no harm in having them backed up just the same.)

Get Updated

On the same train of thought as getting rid of unwanted apps, it also pays to make sure you’re updated to the latest and greatest version of your apps. In the next few weeks, you’ll likely see a flood of new updates as developers release versions that will be fully compatible with all of the goodness inherent in iPhone OS 4.0, so it pays to check for such updates on a regular basis and stay ahead of the curve.

You can check for updates on your device by opening the App Store app; usually after a moment, you’ll see a badge on the Updates tab notifying you of anything new, but sometimes you have to expressly press Updates to refresh them. Note that this will only look for updates for apps you have installed on that particular device -- if you want to check for all app updates, you’ll need to use iTunes. Select the Apps icon in the sidebar and then click the little arrow next to “Check for Updates” in the lower right-hand corner.

Some of us here at MacLife.com are quite diligent about app updates, checking several times a day to see what’s new -- it’s kind of like a mini-Christmas every day, especially when your most-used apps are empowered with cool new features or get annoying bugs squashed. Most app updates are posted in the afternoon and evening, so no sense going around clicking half-cocked in the morning.

One of the better ways to stay abreast of the situation is through a website such as AppShopper.com. The brainchild of the folks behind MacRumors.com, AppShopper lets you create a free account to track your own apps or even create a wish list of ones you might want to buy in the future, as well as providing a wide variety of RSS feeds for both iPhone and iPad to track updates, new apps, price changes and more.

Twitter is another great way to track app updates, since many developers big and small will give a heads-up when new apps or updates have been approved by Apple so you can start exhausting your finger by looking for them on iTunes.

Jailbreakers: Proceed with Caution

Major OS updates are a big deal on any platform, but as anyone who has jailbroken their iDevice knows, even the little updates can create a tsunami of problems for those living on the cutting edge. Thankfully, the hackers are ahead of the curve yet again, and beta builds of iPhone OS 4.0 have already been successfully jailbroken -- but that doesn’t mean you should throw caution to the wind and forge ahead blindly.

If you rely on an unsanctioned, unlocked iPhone for cellular and data access, do yourself a favor and don’t upgrade to OS 4.0 until you get an “all clear” from the hacker community. Just because the beta builds have been jailbroken does not mean that your phone will remain unlocked (in fact, it’s almost a certainty that it won’t), and with new hardware imminent, we don’t know yet if any of the unlocking patches will even work. We repeat: If you’ve unlocked your iPhone, avoid iPhone OS 4.0 until you hear that it’s safe to upgrade!

Whether or not you care about unlocking your iPhone, if you have it jailbroken now or plan to in the future, you should make sure your SHSH blobs are backed up in case you ever want to return to iPhone OS 3.x. Say what?!

Apple has attempted to thwart the hackers by adding extra layers of security in newer devices, in particular the iPhone 3GS, iPad and third-generation iPod touch. If you have one of these devices, you should do yourself a favor and extract the “SHSH” records from your device (they’re different for every single unit), which can be used to restore to older firmware, should things not work out so great with iPhone OS 4.0.

It’s easy to backup your “SHSH blobs” using a free utility called Umbrella and a detailed guide already posted at Cult of Mac -- the whole process takes only a few minutes, so we encourage everyone to do it, even if you don’t plan to jailbreak your device anytime soon.

Save Your Old Firmware

Along the same lines as backing up your SHSH blobs, you’d do well to take a visit to your Home > Library > iTunes > iPhone Software Updates folder and back up whatever .ipsw files you find there. With older versions of iTunes, any iPhone firmware updates were downloaded to this folder and stayed there forevermore, but more recent versions of iTunes will move them to the Trash as soon as you download a new one. There’s a good chance your folder may even be empty already!

The reason you’ll want to save these .ipsw restore files is that shortly after iPhone OS 4.0 is released, Apple will likely wipe all traces of OS 3.1.3 (the latest version) off the map and prevent it from being downloaded again; if you saved your SHSH blobs and ever need to restore to an older version, you’ll need at least one of those old firmware files to do so.

Thankfully, a Google search ought to dig up a number of non-Apple sources for downloading old firmware in the event that yours is already MIA. Keep in mind that you’ll need the appropriate restore file -- the original iPhone will start with “iPhone1,1”, the iPhone 3G will start with “iPhone1,2” and the iPhone 3GS will start with “iPhone2,1”, for instance.

NEXT: Backing up your stuff and organizing your screens. >>