If this is your first Mac, check out the Mac App Store. The process of buying and installing apps is similar to the iPhone. I love it.
Not that you'll need a utility right away, but I swear by Clean My Mac. It's completely safe to use and really does a fantastic job of freeing up space. Since you've got an Air, you will at some point look to maximize your hard drive space, given the smaller size of SSD's. That's exactly where that app excels.
I got the
1.7GHz Dual-Core Intel Core i7, Turbo Boost up to 3.3GHz, 8GB 1600MHz LPDDR3 SDRAM, 128GB Flash Storage, Apple TV and of course Apple care. Thought I was about to have to cancel the order. Me and the girlfriend were on a gravel road and I left my i5 on my trunk. Well forgot it was there when I drove away. Then 20 mins later realized it was gone. It had died so Find My iPhone was useless but we went back and she found it a little ways down the road in a ditch. I was very lucky and super damn thankful she found it.
I've always been big with iPods, iPads and iPhones but never Mac computers. I'm an asst. manager for an e cig company so not a whole lot of money rolling in and they're just expensive lol but saved up for it for 4 months and I think I'm gonna be very happy in my investment.
I bought mine in April and love it, took some getting use to. I subscribe to ScreenCastOnline for great how to videos on a range of topics. The Apple Store is not that close to me, so online was a great way for me to learn.