I clean my screen with rubbing alcohol and a microfiber cloth.
Matt
Rubbing alcohol is CONTRAINDICATED for cleaning the Macbook Air
If you cant get to Costco to buy a few bottles of LCD cleaner with a couple microfibers for $15 then just buy a set of iKlear on Amazon
I bought the iKlear and Microfiber and it has lasted me a very long time. Plus the iKlear solution is great for wiping down the lid, trackpad, keyboard, and wrist area as long as you spray it on the microfiber first and not directly on the laptop itself
For the screen you can spray the screen directly if you want (but it is not recommended). I like to spray a good spray on the cloth and then clean the screen with the cloth wet.
However, the most important thing to know is to clean the screen of any dust or dirt particle first or you risk scratching the screen.
http://www.amazon.com/Klear-Screen-...ie=UTF8&qid=1402097483&sr=1-1&keywords=iKlear
This set comes with three clothes and 8oz of iKlear which should last you a long time. If you spent nearly $1000 for your Macbook Air what's $20 every year or so to clean it