Yesterday the Mac App Store went live with more than 1000 apps already available. Here are a few tips to get you started.

Download the App Store

The Mac App store is available through Software Update, which you can access through the Apple menu. It actually shows up in the list of available downloads as Mac OS X Update Version 10.6.6. You’ll need to restart after installing it, and then the App Store will show up as a new icon in your Dock.

Different ways to access the App Store

If you would prefer not to have an extra icon in your Dock, it’s fine to just drag it out to remove it like you would for any other application. Then if you still want to access the store, there are a number of alternative ways.

A new item “App Store...” is added to the Apple menu, which gives you quick access no matter what application you are in. This also means you can also set a universal keyboard shortcut for it. Just go to System Preferences, go to the Keyboard section, then click on the “Keyboard Shortcuts” tab. Click the plus (+) button to add a new shortcut, and in the dialog that appears, leave the dropdown menu as “All Applications,” Type “App Store...” as the menu title, and then choose a shortcut.

Alternatively, you can access the App Store just like you would any other application. You can just find it in the Applications folder and double-click it, or use Spotlight (Command-Space is a handy shortcut) or any other application launcher like Alfred.

Fixing Error 100

For many people, everything seems to be working fine until they go to download an app, and then they receive a dreaded error message:

We could not complete your App Store request. An unknown error occurred (100).

Luckily it’s easily fixed. It turns out this is because there is a new set of iTunes Terms and Conditions that you have to “read” and agree to, but the App Store doesn’t give you the opportunity to do this. The best solution I found is the following:

1. Quit both the Mac App Store and iTunes.
2. Open iTunes, go to the iOS App Store and download a random free iPhone app.
3. You should be prompted to agree to the new terms and conditions.
4. Delete the iPhone app you just downloaded.
5. Open up the Mac App Store and everything should be fine.

What about applications you already own?

When you download an app through the Mac App Store, the little button next to it changes to “Installed” and the app appears in your purchases section. But what about apps that you already own from before the App Store was around?

It turns out that in general, the App Store recognises that you already have the application, and marks it as “Installed.” However, with some applications (like Pixelmator and Rapidweaver) this doesn’t happen due to the version numbers not matching, and for some this can be fixed by updating the application to the latest version.

Unfortunately, this turns out to be pretty useless. These applications won’t show up in your purchases list, and you won’t be able to re-download or update them through the App Store at all. Unless you want to pay a second time, this means you will have to continue to update these applications in the same way as before - by checking the developer’s website or by using the application’s “Check for Updates” feature.

Of course for free applications, it’s not too much trouble to just download them again through the App Store. If you want to do this with an application that is listed as “Installed,” you will have to drag it from the Applications folder to the Trash and then restart the Mac App Store before you can download it again.

It’s still only iWork ’09

Don’t be fooled by seeing Pages, Keynote and Numbers being sold as separate applications. So far iWork ’11 still doesn’t exist, and these are just the same 2009 versions of the iWork applications. While this is disappointing, it turns out that iWork is the exception to the rule when it comes to updating previously bought applications through the App Store. If you already own iWork ’09, Pages, Keynote and Numbers should sown up in your purchases section and you should be able to update them through the App Store in future.

Finder now searches the store for unknown file types

It’s always been the case that if you try to open an unrecognised file type, a dialog will appear asking you to choose which application to open it with. A new button has now been added that allows you to search the App Store for the application that opens files with that extension. All it does is open up the App Store and perform a search using “extension:” as a filter. For example, if you were trying to open a Pixelmator file, it would search “extension:pxm” bringing up Pixelmator as the only result.

Get some good deals!

You may have noticed that many applications are much cheaper on the App Store than elsewhere. For example, Apple applications like the iWork and iLife suites and Aperture and much cheaper than the boxed versions. Many third-party applications like Pixelmator and Rapidweaver are also much cheaper. It’s hard to say if these prices are only temporary or are here to stay, so it might be worth taking advantage if this while you have the chance.

The downside to lower prices is that free upgrades are likely to become less common in future, meaning you will probably have to spend a lower amount on each version, rather than a big one-off payment at the start.