Turning down the display brightness is the easiest thing you can do, and one of the most effective. Since it's an air it doesn't have an i series processor and lacks the ability to shut off unused cores :/.
The second thing you can do is going into the "power preferences" by clicking on the battery icon on the top right. If the option is available keep "automatic graphic switching" on. this will automatically switch between the video card and integrated video (the integrated drains MUCH less power) based upon context.
The third thing is to put the settings in "power options" into "power saving," but I wouldn't always have it there...it does slow things down a bit.