The answer from @RahulGupta is pretty flawed. You should more follow what @amalBit has written.
As mentioned in my comment, the basic idea is to have a very flexible layout with some basic "cross screen" settings that you can and should follow
For example: The Settings list has on a phone maybe 16-32 dp margin on the sides, on a xlarge tablet like the Nexus 10 it has a way bigger margin. I highly doubt that the Settings screen was built with dozens of dimens files to fit all and every screen resolution, dimension and dpi. I guess that is basically just using one default for all and for the bigger tablets it is using a bigger value. So maybe a differenciation between 320dp and 720dp.
My suggestion: Start small with one layout, one dimens.xml file in your values folder and use a normal phone for your development. When you have done the layouting on it, check it on different screens and see if you need to modify something. Normally on a low res/low dpi device, the paddings/margins and sizes should scale correctly and in a good visual way.
The biggest "issues" you will face with 7"+ tablets and for them I would just start by creating a separate dimens.xml file and increase the dimens I need to make it better looking.
Normally the default values folder should contain 80% of your "style", the rest are just additions to make them fit perfect.