Transfering data to my new mac

I am about to purchase a new macbook air and want to transfer some but not all of the data on my current macbook. My cirrent macbook is at 100Gb and I cant seem to work out where all the data is. I have followed various threads but the yellow portion of the memeory review section is at 60Gb and I cant seem to get it down.

I am thinking that I want to start afresh but want to transfer my applications. I know how to transfer itunes etc.

Depending on the models of Mac you have there are various direct file transfer methods, all based around the migration tool:
OS X Mountain Lion: Transfer your info from a computer or disk